Background of the Present Invention The power saw is a common machine specially used in cutting and shaping tile or other construction materials made of granite, marble, slate, pave, brick, ceramics, and masonry. Referring to Fig. 1, a conventional power saw as illustrated is commonly used in the construction industry for shaping and cutting masonry tiles and the like, made from materials such as granite, marble, slate, ceramics, paver, and brick. The traditional power saw 10 as shown in Fig. 1 includes a cutting table 11 supported on a floor standing frame 12, a cutting head 13 overhanging the cutting table 11 with a circular diamond saw blade 14 which is powered by an electric motor 15. The electric motor 15 is directly mounted on the cutting head 13 for driving the saw blade 14 to rotate using a transmission means 16.

The cutting head arrangement is built around the frame and includes a proximal end attached to the frame and a distal end to which the saw blade is mounted. The saw blade is rotatably mounted to a power output end of the bearing assembly and driven by a drive belt connected between the motor and a power input end of the bearing assembly and driven by a belt drive connected between the motor and a power input end of the bearing assembly.

Liquid coolant must be pumped to the saw blade and the work piece during cutting to reduce the accumulated heat and to flush away sawdust. A nozzle is connected to a

guard that covers a top portion of the saw blade to supply a stream of coolant to the saw blade, wherein the coolant is pumped in from a reservoir. A coolant tray must be installed underneath the cutting table to catch the liquid coolant flowing off of the cutting blade and sludge formed from the coolant mixing with the sawdust.

Besides, liquid coolant that is circulated by pump is usually used to cool the saw blade 14 and work piece and to flush away sawdust. Although such a conventional power saw substantially provides desirable features that include achieving precise and accurate cuts, ease of replacement of the blade when it is worn, rapid adjustment of the saw blade to various positions to permit complex cuts, ease of emptying the tray positioned underneath the saw blade, etc., the conventional cutting saw still contains the following shortcomings.

1. Most power cutting saws break down due to the overheating of the bearing assembly. A great amount of heat is accumulated during the rotary transmission of the bearing assembly that may destroy the internal bearing construction. Normally, if the bearing assembly were continuously working for more than one hour, permanent damage would be caused to the bearing assembly because of overheating.

2. To ensure an excellent cutting performance, the bearings installed inside the bearing assembly must be replaced periodically. But, the conventional bearing assembly fails to provide a detachable feature, so that the user must replace the entire bearing assembly at a higher expense.

3. The conventional power cutting saw requires the user to often remove the coolant tray for emptying the collected coolant therein and cleaning it by dismantling or detaching the cutting table and/or the supporting frame. At present, the most efficient way of removing collected coolant is by pivoting the cutting table onto one side, creating inconvenience for the user.

4. The conventional power cutting saw, including the supporting frame, the cutting table and the cutting head arrangement, is so heavy that even two persons are unable to transport the conventional power cutting saw from a location of use to a transportation vehicle.

5. The motor 15 is positioned above the cutting table 11 and the cutting head 13 supports the heavy weight of the motor 15. Therefore the cutting head 13 must be made of

strong material such as cast iron, or steel alloy to rigidly support the heavy motor 15. The motor supporting cutting head 13 is heavy in weight that also increases the weight of the power saw.

6. The conventional power saw 10 as shown in Fig. 1 is more difficult to transport 5 and operate due to the fact that the major portion of the weight of the whole power saw 10 is its upper part, including the motor 15, the cutting head 13, and the cutting table 11. In other words, the conventional power saw 10 has an unstable structure, i. e. a heavier upper head and a lighter lower support base, that may easily lose balance.

7. The user must be very careful to avoid any body contact with the hot motor 15 exposed above the cutting table 11 to avoid unwanted body injury when the motor 15 is functioning during the operation of the power saw.

Summary of the Present Invention The main object of the present invention is to produce a power saw that comprises a fluid cooling bearing assembly connecting between an electric motor and a saw blade. The fluid cooling bearing assembly contains a built-in fluid cooling system to internally cool down the heat of the bearing assembly so as to prolong the service life span thereof.

Another object of the present invention is to provide a power saw having a fluid cooling bearing assembly, wherein the built-in fluid cooling system shares the fluid pump of the saw blade cooling system and the coolant collecting tray so as to eliminate the unnecessary cost for extra parts.

Another object of the present invention is to provide a power saw having a fluid cooling bearing assembly that can be detached and reassembled easily.

Another object of the present invention is to provide a power cutting saw with a fluid cooling bearing assembly, that has a feature of ease of emptying the coolant tray positioned underneath the cutting table.

Another object of the present invention is to provide a power saw having a detachable supporting frame that enables the user to easily transport the power saw.

Still another object of the present invention is to provide a power saw that has a motor installed in a table frame which is used for supporting the cutting table and the coolant tray, so that the cutting head thereof can be made of light material to reduce the overall weight of the machine.

Yet another object of the present invention is to provide a power saw that has a more stable structure that is more easily to transport and operate, because the major weight of the machine is distributed in the table frame which receives the motor and the coolant tray.

Yet another object of the present invention is to provide a power cutting saw wherein the motor is positioned below the coolant tray such that there is no direct contact between the motor and the user, and such that the coolant tray also provides a cool surrounding near the motor to help cool the motor during operation and reducing the motor's neat output when functioning.

One more object of the present invention is to provide a power saw, which contains an additional supporting means to rotatably support the saw blade above the cutting table thereof.

Accordingly, in order to accomplish the aforesaid objects, the present invention provides a power saw comprising: a table frame; a cutting table attached on the table frame; a supporting frame, which is attached to the table frame, having a transmission chamber; a cutting head having a proximal end and a distal end, wherein the cutting head is supported above of the cutting table by attaching the proximal end to the supporting frame; a fluid cooling bearing system which is firmly secured to a proximate end of the head platform for rotatably mounting a circular saw blade, having an output end and an input end which is extended to an upper position inside the transmission chamber of the supporting frame;

a circular saw blade positioned at the distal end of the cutting head and connected to the output end of the bearing housing assembly of the fluid cooling bearing system; a motor mounted in the table frame having a driving shaft extended to a lower position inside the transmission chamber of the supporting frame; a transmission means disposed in the transmission chamber of the supporting frame for transmitting power outputting from the motor to the input end of the bearing housing assembly so as to drive the saw blade to rotate above the cutting table; and a coolant tray which is supported in the table frame and is disposed beneath the cutting table and above the motor.

The power saw further comprises a fluid pump for pumping fluid coolant from a cooler reservoir, which can be the coolant tray and any other independent container, via a coolant conduit arrangement, to a nozzle connected to a guard that covers a top portion of the saw blade to supply a stream of coolant to the saw blade and the work piece, in order to cool down the accumulated heat during cutting and flushing away saw dust.

The fluid cooling bearing assembly comprises a hollow cylindrical bearing housing which has an axial shaft sleeve and two enlarged bearings cavities provided at two ends of the shaft sleeve to receive two roller bearings therein respectively, and a blade shaft which has a length longer than the bearing housing extending along the shaft sleeve of the bearing housing coaxially and being rotatably supported by the two roller bearings. The saw blade is rotatably mounted on a first end of the blade shaft.

The bearing housing further has coolant chamber embracing around the shaft sleeve, which has a C-shaped cross section and is extended along the shaft sleeve. The bearing housing also provides a coolant inlet and a coolant outlet sealedly connected the cooler chamber with the coolant conduit arrangement. Therefore, the coolant would not only be pumped to cool the saw blade and the work piece to be cut, but also be pumped to flow inside the bearing housing for cooling the rotating blade shaft in order to prevent overheating the rolling bearings.

In order to enhance the cooling effect flowing in the coolant chamber of the bearing housing, a ceiling surface of the coolant chamber is provided in wave form to increase the cooling contact area of the bearing housing.

Moreover, the coolant tray also forms a motor cavity indented thereunder for receiving the motor therein so as to reduce the size of the power saw and to provide a cooling effect around the motor that also generates heat when functioning.

Brief Description of the Drawings Fig. 1 is an elevation view of a conventional power saw.

Fig. 2 is a perspective view of a power saw with fluid cooling bearing assembly according to a preferred embodiment of the present invention.

Fig. 3A is a partial exploded and sectional front view of the power saw according to the above preferred embodiment of the present invention.

Fig. 3B is an enlarged sectional view of the bearing housing in Fig. 3A of the power saw according to the above preferred embodiment of the present invention.

Fig. 4 is a left side view of the power saw according to the above preferred embodiment of the present invention.

Fig. 5 is a sectional view of the bearing housing of the fluid cooling bearing assembly of the power saw according to the above preferred embodiment of the present invention.

Fig. 6 is a partial enlarged view of the cutting head arrangement to illustrate the coolant conduit arrangement according to the above preferred embodiment of the present invention.

Fig. 7 is a perspective view of a first alternative mode of the power saw with fluid cooling bearing assembly according to the above preferred embodiment of the present invention.

Fig. 8 is an exploded perspective view of a power saw with fluid cooling bearing assembly with floor standing frame according to a second preferred embodiment of the present invention.

Fig. 9 is a perspective view of a power saw machine according to a second preferred

embodiment of the present invention.

Fig. 10 is a perspective view of the table frame of the power saw machine according to the above second preferred embodiment of the present invention.

Fig. 11 is top view of the power saw machine according to the above second preferred embodiment of the present invention.

Fig. 12 is a side view of the power saw machine according to the above second preferred embodiment of the present invention.

Fig. 13 is a side view of the power saw machine with the coolant tray pulling out according to the above second preferred embodiment of the present invention.

Fig. 14 is a side view of a first alternative mode of the power saw machine according to the above second preferred embodiment of the present invention.

Fig. 15 is a side view of a second alternative mode of the power saw machine according to the above second preferred embodiment of the present invention.

Detailed Description of the Preferred Embodiment Referring to figures 2 through 7 of the drawings, a power saw which is specifically designed for ceramic and masonry work pieces such as tiles according to a preferred embodiment of the present invention is illustrated. The power saw comprises a cutting table 60 slidably mounted on a table frame 20 which has four legs 21,22,23,24 detachably connected thereunder, a coolant tray 84 disposed underneath the cutting table 60 and a cutting head arrangement 40 supported above the cutting table 60. The cutting head arrangement 40 includes a head platform 41 pivotally mounted on the table frame 20 by means of a pivot arm 42 affixed at one side of the table frame 20, a motor 43 mounted on a distal end of the head platform 41, a fluid cooling bearing assembly 50 which is firmly secured to a proximate end of the head platform 41 for rotatably mounting a circular saw blade 6, and a transmission means 70 for transmitting the rotating power of the motor 43 to the fluid cooling bearing assembly 50. According to the present embodiment, the transmission means 70 comprises an endless transmitting member 73 connected between the motor 43 and the fluid cooling bearing assembly 50.

As shown in Figs. 2 and 5, the power saw further comprises a fluid pump 81 immersed in the coolant provided in a coolant reservoir, which can be any other independent container or the coolant tray 84 according to the present embodiment, for pumping fluid coolant from the coolant reservoir (coolant tray) 84, via a coolant conduit arrangement 80, to at least a nozzle 821 connected to a blade protective shell 33 that covers a top portion of the saw blade 6 to supply a stream of coolant to the saw blade 6 and the work piece to be cut or shaped in order to cool down the accumulated heat during cutting and flushing away saw dust. The coolant can be any lubricant with cooling effect or simply water.

Referring to Figs. 3A, 3B and 5, the fluid cooling bearing assembly 50 comprises a hollow cylindrical bearing housing 51 and a blade shaft 52. The bearing housing 51 has an axial shaft sleeve 511 and two enlarged bearings cavities 512,513 provided at two ends of the shaft sleeve 511 to mount two roller bearings 532,533 therein respectively. The blade shaft 52, which has a length longer than the bearing housing 51, coaxially extends along the shaft sleeve 511 and is rotatably supported by the two roller bearings 532,533. A seal bracket 534 is mounted on the shaft sleeve 511 before the roller bearing 533 to permanently seal the bearing housing 51. An inner flange 541 is mounted on the blade shaft 52 to support the saw blade 6, which is rotatably mounted on a first end 521 of the blade shaft 52. An outer flange 542 is also mounted on the blade shaft 52 to hold the saw blade 6 in position by securing a lock nut 54 to a threaded portion of the first end 521 of the blade shaft 52. A pulley 55 is rotatably mounted on a second end 523 of the blade shaft 52 and driven by the endless transmitting member 73.

As shown in Figs. 3B and 5, the bearing housing 51 further has a coolant chamber 514 embracing around the shaft sleeve 511, which has a C-shaped cross section and is extended along the shaft sleeve 511. The water seal bracket 534 is adapted to keep the coolant recycled within the coolant chamber 514. The bearing housing 51 also provides a coolant outlet 516 sealedly connecting the coolant chamber 514 with the coolant conduit arrangement 80, as shown in Fig. 6. Therefore, the coolant would not only be pumped to cool the saw blade 6 and the work piece to be cut, but also be pumped to flow inside the bearing housing 51 for cooling the bearing housing 51 in order to prevent overheating of the two roller bearings 532,533. As shown in Fig. 3B, the bearing housing 51 further has a control screw 518 screwed thereunder.

As shown in Figs. 4 and 6, there are two nozzles 821,822 respectively attached to a central position of the blade protective shell 33 for enabling the coolant to discharge to the inner flange 541 and a front position of the blade protective shell 33 for enabling the coolant to discharge to the saw blade 6. The coolant conduit arrangement 80 is connected between the fluid pump 81 and the two nozzles 821 and 822 for transmitting the coolant pumped from inside the coolant tray 84 by the fluid pump 81 to discharge through the two nozzles 821,822.

According to the present embodiment, for better circulation, a coolant inlet 515 is a lower hole penetrating through a lower portion of the bearing housing 51 into a lower half of the coolant chamber 514 and the coolant outlet 516 is an upper hole penetrating through an upper portion of the bearing housing 51 into an upper half of the coolant chamber 514.

Therefore, coolant enters the lower half of the coolant chamber 514 through the coolant inlet 515 and flows to the upper half of the coolant chamber 514 in order to exit the coolant chamber 514 through the coolant outlet 516. Therefore, almost the entire shaft sleeve 511 is surrounded by the flowing coolant inside the coolant chamber 514 so as to cool down the heat generated by the two rotating roller bearings 532,533 and transferred to the bearing housing 51.

In order to enhance the cooling effect of the coolant flowing in the coolant chamber 514 of the bearing housing 51, a ceiling surface of the coolant chamber 514 is provided in wave form to form a plurality of downwardly protruding fins 5142 so as to increase the cooling contact area of the bearing housing 51. Moreover, since heat transferred in the bearing housing 51 will flow up to the upper half thereof, the protruding fins 5142 formed on the ceiling surface of the coolant chamber 514 have a function of collecting and dissipating the heat in the bearing housing 51 to the coolant flowing within the coolant chamber 514.

As shown in Fig. 2,3B, 5 and 6, the proximate end of the head platform 41 provides four locking holes 411 (as shown in Fig. 6). The bearing housing 51 has four vertical securing through holes 517 (as shown in Figs. 3B and 5). A securing means which comprises four locking bolts 44, a steel made locking plate 45 and four locking nuts 46 is used to firmly mount the fluid cooling bearing assembly 50 to the proximate end of the head platform 41.

The locking plate 45 is specifically shaped to attach on a bottom side of the bearing housing 51. As shown in Figs. 2,5 and 6, the four locking bolts 44 are respectively penetrated through the four locking holes 411 on the head platform 41, and the four securing through holes 517 of the bearing housing 51 and the locking plate 45. The four locking nuts 46 are

respectively screwed to the four locking bolts 44 so as to firmly secure the bearing housing 51 with the proximate end of the head platform 41. Since the best material of the bearing housing 51 is aluminum for better heat dissipation, the locking plate 45 can prevent the locking nuts 46 from damaging the bearing housing 51 while tightly screwing against the bearing housing 51.

As shown in Fig. 6, the coolant conduit arrangement 80 comprises a first conduit 801 connected between the fluid pump 81, having a filtering function, and the coolant inlet 515 of the bearing housing 51 via the pivot arm 42 and the head platform 41, a second conduit 802 which is extended through the head platform 41 and the blade protective shell 33 for connecting the coolant outlet 516 of the bearing housing 51 with the first nozzle 821 that is attached to the blade protective shell 33 in a position adjacent to the blade surface of the saw blade 6, a third conduit 803 which is disposed within the blade protective shell 33 for connecting the second conduit 802 with the second nozzle 822 that is attached to the central portion of the blade protective shell 33 in order to discharge coolant to the inner flange 541, a by-pass conduit 804 connected between the first conduit 801 and the second conduit 802 and adjacent to the coolant inlet 515 and the coolant outlet 516, a control valve 82 is connected to a junction of the second conduit 802 and the third conduit 803 so that when the control valve is shut, no coolant will be flow to the first and second nozzles 821,822, and a return conduit 817 connected from the second conduit 802 (i. e. the coolant outlet 516) to the coolant tray 84.

Accordingly, coolant in the coolant tray 84 is pumped by the fluid pump 81 to enter the coolant chamber 514 of the bearing housing 51 via the first conduit 801. The incoming coolant inside the coolant chamber 514 is used to dissipate the heat transferred from the rotating roller bearings 532,533 by flowing inside the bearing housing 51. The coolant inside the coolant chamber 514 flows up to exit through the coolant outlet 516.

When the control valve 82 is opened, the coolant emitted from the coolant outlet 516 flows into the second conduit 802 that will further transmit the coolant to the first nozzle 821 and the second nozzle 822 via the third conduit 803. The first nozzle 821 supplies a stream of coolant to the saw blade 6 for cooling down the saw blade 6 and flushing away sawdust. The second nozzle 822 also supplies a stream of coolant to the inner flange 541 so as to prevent the heat generated in the saw blade 6 during cutting from transferring to the fluid cooling bearing assembly 50.

The coolant flowing off of the saw blade 6 and the sludge formed from the coolant mixing with the sawdust are collected in the coolant tray 84 placed beneath the cutting table 60. When the power saw is switched off, the by-pass conduit 804 forms a fast passage for the coolant returning to the coolant tray 84 so as to ensure no coolant will leave in the second and third conduits 802,803 and within the coolant chamber 514.

The coolant flow can be adjusted by the control valve 82 so as to adjust the volume of coolant flow or to stop the coolant from flowing to the first and second nozzles 821,822.

When the user desires a dry cut under certain conditions such as in-house working environment and masonry cutting, the control valve 82 can be shut to stop coolant flowing from the coolant outlet 516 of the fluid cooling bearing assembly 50 to the first and second nozzles 821,822. Under such conditions, the coolant flowing out of the coolant outlet 516 will return to the coolant tray 84 via the return conduit 817.

When the user needs to clean the bearing housing 51, the following steps can be processed. First, unscrew the control screw 518. Second, close the control valve 82. Third, bend the return conduit 817 connected to the coolant outlet 516. Accordingly, the pump can reverse the coolant flow and clean the dirt in the bearing housing 51.

As shown in Fig. 6, a plastic brush 83 is attached to the front portion of the blade protective shell 33 that holds the both sides of the saw blade 6 in order to keep the coolant staying on the surfaces of the saw blade 6 and cleaning the saw blade 6 before it cuts the work piece. Besides, the plastic brush 83 has feature of limiting the coolant flowing wide spread due to the high speed rotation of the saw blade 6.

As shown in Figs. 2,3A and 4, the coolant tray 84 is placed on the table frame 20 which comprises a pair of side rails 25,26 affixed to two opposing sides thereof to enable the cutting table 60 to slide along the side rails 25,26 of the table frame 20. One of the side rails 25 also features for holding the coolant tray 84 in position. Adjacent to the other side rail 26, a holding bracket 27 is pivotally mounted to the to an opposite side of the table frame 20 to hold the coolant tray 84 inside the table frame 20. However, the holding bracket 27 can be pivoted up to enable the coolant tray 84 to be removed side-way-out of the table frame 20 for refilling coolant and cleaning purposes, as shown in Fig. 3. Another advantage of the holding bracket 27 is to protect the coolant tray 84 from being hit during transportation.

As shown in Figs. 2 and 4, two auxiliary wheels 91 are affixed to a rear end of the table frame 20; two rolling wheels 92 are respectively affixed to bottom ends of the two legs 23,24, which are attached to a rear end of the table frame 20. The four legs 21 to 24 are connected under the table frame 20 by inserting their top ends, respectively, into a set of four receiving tubes 201-204 provided at the four corners of the table frame 20. Therefore, when the user has to transport the power saw by a transportation vehicle such as a pick-up truck, the user may first push or pull the power saw near the pick-up truck and place the two auxiliary wheels 91 on the edge of the pick-up truck. Then, the user may detach the two rear end legs 23,24 from the table frame 20. Afterwards, the user can easily push the heavy body of the power saw on the pick-up truck by means of the two auxiliary wheels 91. Finally, the user may detach the two front end legs 21,22 from the table frame 20. The user may reverse the above steps to also easily unload the power saw from the transportation vehicle. Moreover, the user may lift up the power saw, with all the legs 21 to 24 removed, to a 45 degree position, so that the power saw can also be carried on floor surface of the job site by rolling the power saw on the two auxillary wheels 91 by only one person without any help.

Referring to Fig. 7, an alternative mode of the above preferred embodiment is illustrated, wherein the fluid pump 81 is disposed in an additional coolant container 841 for supplying coolant to the fluid cooling bearing assembly 50 via the first conduit 801. It is especially practical when dry cut is required, wherein the control valve 82 is shut, so that the coolant will be pumped by the fluid pump 81 from the coolant container 841 to merely recycle inside the coolant chamber 514 of the bearing housing 51 of the fluid cooling bearing assembly 50. The coolant exiting from the coolant chamber 514 will all be collected and sent back to the coolant container 841 via the return conduit 817. Therefore, the saw blade can be kept continuously cutting without overheating the bearings 532,533.

In view of the above disclosure of the preferred first embodiment, it is apparent that the present invention can achieve the following advantages: (1) The fluid cooling bearing assembly contains a built-in fluid cooling system to internally cool down the heat of the bearing assembly that can prolong the service life span thereof.

(2) The built-in fluid cooling system shares the fluid pump of the saw blade cooling system and the coolant collecting tray so as to eliminate the unnecessary cost for extra parts.

(3) The fluid cooling bearing assembly can be detached and reassembled easily.

(4) The power saw has a feature of ease of emptying the coolant tray positioned underneath the cutting table.

(5) The power saw has a detachable supporting frame that enables the user to easily unloading from or putting on a transportation vehicle.

Referring Figs. 8 to 13 of the drawings, a power saw according to a second preferred embodiment of the present invention is illustrated, which comprises a table frame 20', a cutting table 60', a supporting frame 61, a cutting head 30, a bearing housing assembly 56, a circular saw blade 6', a motor 43', a transmission means 70', and a coolant tray 84'.

As shown in Figs. 8 to 10, the table frame 20'comprises a bottom frame 29, four receiving tubes 201', 202', 203', 204'upwardly extended from four corners of the bottom frame 29, a sliding rail 25'connected between two receiving tubes 202', 204'attached to a first side of the bottom frame 29, and a supporting rail 26'which is parallel to the sliding rail 25'and connected between another two receiving tubes 201', 203'attached to a second side of the bottom frame 29.

As shown in Figs. 8,9 and 11, the cutting table 60'is slidably mounted on the table frame 20'. The cutting table 60'comprises a work table 601 sitting across the sliding rail 25' and the supporting rail 26'of the table frame 20', and a sliding arrangement 602 for enabling the work table 601 to slide along the sliding rail 25'and the supporting rail 26'.

As shown in Figs. 8,9 and 10, the supporting frame 61, which is vertically attached to the table frame 20', has a bottom end 611 and a top end 612, wherein the bottom end 611 is firmly affixed to the first side of the bottom frame 29 of the table frame 20'. A transmission chamber 62 is defined inside the supporting frame 61.

The cutting head 30 comprises a head frame 31 having a proximal end 311 and a distal end 312, wherein the cutting head 30 is horizontally supported above of the cutting table 60 by integrally affixing the proximal end 311 of the head frame 31 to the top end 612

of the supporting frame 61. As shown in Figs. 8 and 12, below the head frame 31, the bearing housing assembly 56 is rigidly secured thereto. The bearing housing assembly 56 has an output end 561 and an input end 562 which is extended to an upper position inside the transmission chamber 62 of the supporting frame 61. As shown in Figs. 8 and 12, the saw blade 6'which is positioned at the distal end 312 of the head frame 31 of the cutting head 30 is connected to the output end 561 of the bearing housing assembly 56.

As shown in Figs. 8,9,11, and 12, the cutting head 30 further comprises a controlling head 32 mounted on the head frame 31 for covering the head frame 31 and the bearing housing assembly 56 secured thereunder. Other electrical controlling means 321 such as circuit control, fuse and controlling switch are installed therein for controlling the operation of the machine. A blade protective shell 33', which is in semi-circular shape, has a connecting end 331 pivotally connected to a rear end of the controlling head 32 for normally covering a top portion of the saw blade 6'. The blade protective shell 33 can be upwardly rotated with respect to the connecting end 331 for replacing the saw blade 6'when it is worn out.

As shown in Figs. 8 and 10, the motor 43'is firmly mounted on the bottom frame 29 of the table frame 20', wherein the motor 43'is aligned in parallel with the cutting head 30 so as to extend a driving shaft 90 of the motor 43'into a lower position of the transmission chamber 62 of the supporting frame 61, as shown in Fig. 10, according to the second preferred embodiment of the present invention. In order to protect the motor 43', a motor protective housing 93 is used for covering the motor 43', wherein the motor protective housing 93 comprises a motor shell 931 attached to the bottom frame 29 to cover the motor 43'and an end cover 932 attached to a distal end of the motor shell 931.

In view of the foregoing disclosure, the input end 561 of the bearing housing assembly 56 and the driving shaft 90 of the motor 43'are respectively extended to the upper and lower positions inside the transmission chamber 62. As shown in Fig. 8, the transmission means 70'is disposed in the transmission chamber 62 of the supporting frame 61 for transmitting power outputting from the motor 43'to the input end 562 of the bearing housing assembly 56 so as to drive the saw blade 6'to rotate above the cutting table 60'.

As shown in Fig. 8, the transmission means 70'comprises a first transmitting wheel 71 and a second transmitting wheel 72 rotatably connected to the driving shaft 90 of the motor 43'and the input end 562 of the bearing housing assembly 56 inside the transmission

chamber 62, and an endless transmitting member 73'disposed inside the transmission chamber 62 for connecting the first transmitting wheel 71 with the second transmitting wheel 72. According to the second preferred embodiment as shown in Fig. 8, the transmitting member 73'is a transmitting belt and the first and second transmitting wheels 71,72 are two belt pulleys.

As shown in Figs. 8 and 10, the transmission means 70'further comprises a belt tension adjusting unit 74, which is installed inside the transmission chamber 62 of the supporting frame 61, for maintaining the transmitting tension of the belt-type transmitting member 73'. The belt tension adjusting unit 74 comprises a pressure pulley 741, which is supported in the transmission chamber 62 to press against the belt-type transmitting member 73'. The belt tension adjusting unit 74 further comprises a supporting bridge 742 extended across the transmission chamber 62, wherein an inclined Z-shaped hole 743 is provided on the supporting bridge 742, so that the user may adjust the pressure applied to the transmitting member 73'by locking the pressure pulley 741 at different positions of the Z-shaped hole 743 so as to adjust the transmitting tension of the transmitting member 73'.

It should be understood that two chain gears can substitute the two belt pulleys when a transmitting chain is used as the transmitting member 73'. In other words, the transmitting member 73'is adapted for connecting the driving shaft 90 of the motor 43'with input end 562 of the bearing housing assembly 56 so that the motor 43'can drive the saw blade 6'to rotate through the power transmission of the driving shaft 90, the transmission means 70'and the bearing housing assembly 56.

The coolant tray 84'is supported in the table frame 20'and disposed beneath the cutting table 60'and above the motor 43'. As shown in Figs. 8 to 13, the coolant tray 84'has a size equal to or slightly smaller than the bottom frame 29 and a depth slightly smaller than the distance between the bottom frame 29 and the sliding rail 25'and the supporting rail 26'.

The coolant tray 84'is placed on the bottom frame 29 and guided by the sliding rail 25'and supporting rail 26', as shown in Figs. 9 and 11. Inclined surfaces 842 are provided at two ends of the coolant tray 84'for facilitating coolant circulation. Moreover, a bottom side of the coolant tray 84'defines a motor cavity 843 which has a size fitting to receive the motor 43' therein when the coolant tray 84'is sat on the bottom frame 29, so that the top, front, rear, and right sides of the motor 43'are substantially surrounded by the coolant tray 84'. In other

words, the coolant tray 84'can also provide a cooling effect for the motor 43'located thereunder to dissipate the heat generated from the motor 43'when it is functioning.

As shown in Fig. 13, the coolant tray 84'can also be pulled out from the table frame 20'for cleaning or replacing the liquid coolant therein.

As shown in Figs. 8 and 10, liquid coolant is filled in the coolant tray 84'and is circulated by a fluid pump 81'that is disposed in the cooling tray 84'to cool the cutting saw 6'and work piece and to flush away saw dust.

The power saw of the present invention as shown in Fig. 9 can be simply placed on a worktable of the user. However, as shown in Fig. 8, the power saw of the present invention may further comprise a floor standing frame 28'which includes four standing legs 21', 22', 23', 24'respectively connected with the four receiving tubes 201', 202', 203', 204'for supporting the machine on floor. During transpiration or storage, the user may detach the four standing legs 21'to 24'by pulling them out from four receiving tubes 21'to 24'to save space.

Referring to Fig. 14, a first alternative mode of the second preferred embodiment is illustrated, wherein an additional saw blade supporting means 34'is used to reinforce the supporting of the saw blade 6'. The additional saw blade supporting means 34'comprises a L-shaped supporting arm 341'having a top end supporting saw blade 6'and a bottom end pivotally connected to the second side of the bottom frame 29 of the table frame 20'. As shown in Fig. 15, when a larger tile needs to be cut, the additional saw blade supporting means 34'further comprises a supporting bar 342'supported and extended between the saw blade 6'and the top end of the supporting arm 341'.

According to the above disclosure, the following advantages can be concluded over prior arts.

First, the overlapping of the coolant tray 84'with the motor 43'can reduce the size of the power saw for easy storage and transportation. Practically, the power saw of the second preferred embodiment of the present invention, with the four standing legs detached, can even be fitted into a car trunk.

Second, due to the fact that the bottom frame 29 of the table frame 20'must have a strong construction for supporting the coolant tray 84'and the liquid coolant therein, therefore the motor 43'can be well supported by affixing on the bottom frame 29. In other words, according to the present invention, the supporting frame 61 and the head frame 31 of the cutting head 30 only need to support the bearing housing assembly 56 and the saw blade 6'but do not need to support the heavy motor anymore. Therefore, both the supporting frame 61 and the cutting head 30 can be constructed by light material that can largely reduce the weight of the power saw. In fact, for the same cutting power, a conventional power saw as shown in Fig. 1 normally weight 100 to 110 lbs. but the present invention as shown in Fig. 3 has a weight of 50 to 60 Ibs. only.

Third, since the motor 43'is placed under the coolant tray 84', so that the coolant tray 84'can collect any coolant spilling or dropping down, so that the drawback of the conventional power saw that the liquid coolant that may spill on the motor affixed on top of the cutting head can thus be avoided.

Fourth, an unexpected cooling effect for the motor 43'is achieved in the present invention. The liquid coolant in the coolant tray 84'is used for heat dissipation and the motor will generate heat during function. For the conventional machine, the coolant does nothing to the hot motor. However, according to the present invention, the motor 43'is surrounded by the coolant tray 84'wherein the liquid coolant in the coolant tray 84'may help dissipating the heat generated from the motor, so as to prolong the service life span of the motor.

Fifth, the power saw of the present invention is more easily to assemble since it is easier to affix the heavy motor 43'on the large bottom frame 29 than to mount on the small cutting head. The manufacturing cost of the present invention is also lower by eliminating the strong, heavy and expensive construction of the cutting head framework.

Sixth, the risk of the user being burnt by the heat of the motor of the prior art is eliminated because the motor 43'of the present invention is stored under the coolant tray 84'.

It is understood that the fluid cooling bearing system 50 may also be used in the second preferred embodiment to act to cool the bearing housing assembly 56 of the second preferred embodiment.