Motor driven power tool

Abstract: A power tool (1) wherein an integrated pressure fluid motor (13) is provided with a unitary motor cylinder 15 and back head (36) and an external co-operating porting surface for co-operating with a valve porting surface. Also provided is a co-operating front head plate (75) with concentric alignment lands for attachment of the motor and a power output device (19) such as a gear reducer or impact wrench.

Description: This invention relates generally to a motor driven power tool and more particularly to an integrated motor cylinder, back plate and controller for control of pressure to a pneumatically-operated, hand-held, power tool. In the past, construction of pressure fluid driven power tools has been accomplished by assembly of individual components requiring assembly time and critical alignment. In addition, tolerances and stress have served to distort the assembled units. US-A-5 017 109 discloses a pneumatic tool having features in accordance with the precharacterising portion of claim 1. According to the present invention, there is provided a motor driven power tool comprising a reversible, pneumatic motor, the motor having a one piece motor cylinder and back head provided with an external valve porting surface for co-operative contact with a pressure fluid regulator for selectively admitting motive media to said motor, characterised by a rotary reversing valve which slidably co-operates with a valve plate having a forward supply port and a reverse port; and a pressure fluid regulator being movably mounted in the back head. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a sectional side view of a power regulated power tool, Figure 2 is a plan view showing an integrated cylinder back plate and controller cavity construction, Figure 3 is an underneath view of the cylinder construction showing a co-operating valve surface, Figure 4 is a front end view of the cylinder, Figure 5 is a rear end view of the cylinder construction, Figure 6 is a cross-sectional view of the cylinder construction taken along line A-A of Figure 4, Figure 7 is a cross-sectional view of the integrated cylinder taken along line B-B of Figure 6, and Figure 8 is a cross-sectional view taken along line C-C of Figure 6. Referring to Figure 1, an impact wrench power tool 1 is shown in section. The power tool 1 is provided with a handle 2 having a pneumatic fluid or air inlet 33 for providing motive fluid to a pneumatically-operated motor or air motor 13. Air is supplied to the air motor through an air inlet passageway 4. A tilt valve 5 is operated by means of a trigger 6 to admit pressure fluid to a chamber 9. Disposed within the chamber 9 is a rotary spool element 10 performing as a reversing valve for selectively distributing pressure fluid to a forward supply port 20 or optionally a reverse port 21 (shown in Figure 3) hidden behind the forward port 20 at a position approximately opposite the forward port in a valve plate 12. The reversing valve spool 10 is provided with a planar segmented end 11 which slidably co-operates with the planar surface of the plate 12. Air entering the forward or reverse ports 20 or 21 selectively proceeds to drive the air motor 13 in forward or reverse direction as the air is expanded against motor vanes 14 in the motor cylinder 15. The motor rotates on bearings 16 and 16' to drive an output shaft 17. The output shaft 17 drives a work output device such as a rotating frame 18 of an impact clutching device which, through the clutch, drives a square drive work output device 19. Alternatively, the output shaft 17 may drive an alternative work output device such as a gear reducer or the like. It will be appreciated that rotating the reversing valve spool 10 approximately 90 degrees by depressing either a forward pushbutton 30 or a reverse pushbutton 25 will align the spool passageway with one or the other ports 20 or 21 leading to either the forward or reverse chambers of the motor. Rotating the reversing valve spool 10 will therefore accomplish direction of flow of motive fluid to either forward or reverse drive the motor. Expanded air exhausts the motor via exhaust passageway or ports 7 which eventually exits through a handle exhaust passageway 41 and exhaust screen or muffler 42 to atmosphere. Referring to Figure 1, a bypass power regulator 40 is shown installed at the back end of the power tool in line with the motor. The regulator may be described as an irregular cylinder closed at one end having a knob 31 formed on the closed end to facilitate its rotation about its cylindrical axis in a tool bore. The periphery of the regulator 40 towards the open end is provided with a series of power regulating steps. These steps co-operate with the forward pressure fluid supply port to permit a greater or lesser degree of pressure fluid to bypass the motor from essentially zero to a maximum. The regulator cylinder is also provided with an axially extending indexing finger 35 which co-operates with a series of indexing indentations 36, 36', 36'' and 36''', formed in the rear of the back head, as best seen in Figure 5. As previously stated, the bypass regulator 40 is installed in the cylindrical bore 37 and is free to rotate therein. The rotary position of the bypass regulator may be selected by turning the knob 31 to the desired position to obtain the degree of power output required. The selected position is retained by the index finger 35 co-operating with the index positioning grooves 36 et seq. as previously described. The porting provided in the casing of the power tool utilises formed interspaced channels within the housing and are difficult to depict in planar presentation. However, for purpose of describing the present construction, it is sufficient to understand that co-operating fluid flow channels are provided in the tool casing 3 to effect the supply of pressure fluid to the motor in the forward direction and the reverse direction and to permit both the primary and second exhaust of pressure fluid from the tool. The present invention is directed particularly towards the construction of the air motor and the associated reversing valve planar surfaces. As shown in Figures 2 to 8, the motor cylinder 15, back head 26, the cylindrical bore 37 for the power regulator, and a bore 27 for the rear bearing 16', are provided in an integral, one-piece structure. In addition, a number of internal distribution ports are provided in the integral structure, for example, inlet forward and reverse ports 20 and 21, respectively, are provided in valve plate 12, as previously described. These ports co-operate and provide pressure fluid to the forward inlet passageway 50 and reverse inlet passageway 51. The inlet passageways 50 and 51 communicate respectively with a forward supply slot 60 and a reverse slot 61 provided in an interior cylinder wall 45. The back plate 26 is further provided with a pair of semi-circular ports 70, 71, seen in Figures 4 and 6, which communicate with the vane slots of the air motor 13 to assist the blades 14 outward during forward and reverse operation respectively. Drilled cross ports 72 and 73 are provided in the end plate 26 to communicate between the inlet passageways 50 and 51 and the semi-circular ports 70 and 71, respectively, as seen in dotted lines in Figure 5. A bore 55 is provided in the end plate 26 to permit the output shaft 17 to pass through the end plate for support in the bearing 16' which in turn is supported in a bearing boss 28 which extends from the back plate 26, as seen in Figures 5 and 6. To complete the motor assembly, the cylinder assembly co-operates with a centralising bore 49 in the forward end plate and forward bearing retainer 75, as seen in Figure 1. As may be appreciated, the forward end plate 75 forms a convenient device for the concentric assembly of the impact clutching device 29 and its casing 39. The casing 39 also forms the nose of the power tool. The construction herein described provides for a convenient and economical method of power tool assembly and further includes a valve planar plate surface for the co-operation of a spool type supply. The features of the valve construction permit ready assembly and alignment of the critical parts. The assembly may be readily bolted together by means of axially extending tie bolts. Four notches 49 are shown provided in the peripheral surface of the cylinder and forward end plate 75 for the purpose of receiving the axially extending tie bolts and for radially positioning the cylinder assembly relative to the housing 3 and the front plate 75.

Claims: A motor driven power tool (1) comprising a reversible, pneumatic motor (13), the motor having a one piece motor cylinder (15) and back head (26) provided with an external valve porting surface (37) for co-operative contact with a pressure fluid regulator (40) for selectively admitting motive media to said motor, characterised by a rotary reversing valve (10) which slidably co-operates with a valve plate (12) having a forward supply port (20) and a reverse port (21); and a pressure fluid regulator (40) being movably mounted in the back head (26). A tool according to claim 1, wherein said motor cylinder and back head further includes means (27) for bearing support. A tool according to claim 1 or 2, wherein said motor cylinder and back head further includes a circumferential mating surface on said unitary structure for mating with a front end plate (75) of said motor. A tool according to claim 3, wherein said front end plate (75) is further provided with a bearing mounting means for mounting a front bearing (16). A tool according to claim 4, wherein said front bearing (16) and a rear bearing (16') mounted in said one piece motor cylinder and back head provide aligned rotation for said motor in the tool. A tool according to claim 3, 4 or 5, wherein said front end plate (75) further provides a mounting means for a work output device (19). A tool according to claim 6, wherein said work output device is in the form of an impact clutch.

Inventors: CLAPP JOHN M, GEIGER ROBERT E, CLAPP, JOHN M., GEIGER, ROBERT E.
Applicants: INGERSOLL RAND CO, INGERSOLL-RAND COMPANY
Application year: 1993
Main classification: B25F5
IPC codes: B25B21, B25F5