US2231496A - Percussive tool - Google Patents

Description

G. H. FUEHRER Feb. 1l, 1,941;

PERCUSSIVE TOOL Filed Dec.

Patented Feb. 11, 1941 UNITED STATES.

PATENT oFFicE v2,231,496 v PERCUSSIVE TOOL Application December 1, 1938, Serial-No. 243,368

5 Claims.

This invention relates to percussve tools, and more particularly to a percussive tool of the type that is held to the work and guided by the operator.

One object of the invention is to make possible a nice control of the valve mechanism effecting the distribution of pressure fluid to the percussive element of the tool.

Other objects will be in part obvious and in part pointed out hereinafter. v

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts- Figure 1 is a longitudinal View, partly in section, of a percussive tool constructed in accordance with the practice of the invention and showing the pressure fluid controlling and distributing devices in operative positions,

Figure 2A is a view similar to Figure 1 showing the pressure iiuid controlling and distributing devices in the positions which they will occupy during the time the percussive tool is idle, and

Figure 3 is a transverse View taken through Figure 1 on the line 3 3.

Referring more particularly to the drawing, the percussive tool, designated in general by 20, comprises a cylinder 2| havingl a forwardly reduced extension 22 which is provided with external threads 23 for engagement with threads 24 of a front head 25 forming the foremost casing portion of the tool.

The interior of the cylinder 2|! constitutes a piston chamber 26 and a hammer piston 21 is reciprocable in the piston chamber 26 to deliver blows to the shank 28 of a working implement 29 extending into the front head 25. An exhaust port 30, in an intermediate portion of the cylinder 2|, is controlled by the piston 21 and in the outer surface of the cylinder 2| is an annular groove 3| to accommodate a muffler in the form of a split sleeve 32 for damping the noise of the exhaust uid issuing from the exhaust port 30.

In the front end of the cylinder 2| is a bushing 33 to guide the shank 28 of the Working implement, and on the forward end of the bushing is an external flange 34 which is clamped between the end of the cylinder and a shoulder 35 in the front head to secure the bushing 33 in position. The bushing 33 serves as a stop for a collar 3S on the working implement, and in the forward extremity of the front head is a bushing 31 to serve as a guide for a portion of the working implement lying forwardly of the collar 36.

The rearward end of the piston chamber 26 is closed by a wall 38 which is an integral portion of the cylinder, vand. `at diametrically opposite sides of the wall 38 and integraltherewith and with the cylinder 2| are legs 39 and 40 which are joined by a bar 4| to serve as a grip member for the operators hand.

In accordance-with the practice of the invention, the leg 40 is kprovided With a bore 42 that extends into an enlargement 43 on the side of the cylinder 2| to accommodate the valve mechanism whereby fluid distribution to the piston chamber 26 is controlled. The valve mechanism comprises a Valve chest 44 in the form of a plug which may be press fitted or otherwise suitably secured in the bore 42.` The plug 44 extends with its rearmost end into the plane of the bar 4| and is boredinvits forward portion to forma valve chamber 45-which is closed at its front end by a` plug 46 seating against the bottom of the bore 42. In the rearward end of the valve chamber 45 is a valve 41 which reciprocates in the valve chamber to distribute pressure nui-d to the piston chamber 26. 'I'he valve 41 is of the spool type having a pair of end flanges 48 and 49 and a stem 50 connecting theflanges. The flanges 48 and 49 are of the same-diameter. Their outer end surfaces constitute 4pressure areas 5| and 52, respectively, against which air compressed by the piston 21 acts to actuate the valve and such oompressed air is. carried to the surfaces 5| and 52 by passages 53 and 54, respectively, which also serve tov conveypressure fluid from the valve chamber to the ends of the piston chamber.

A recess 55'in the plug 44, forming a continuation of the passage 54, opens into the rearward end of the valve chamber 45, and at the juncture of the recess 55 with the valve chamber 45 is a shoulder 56 that-Serves as a valve stop or seat which the flange 49 engages to limit therearward. travel of the valve.

The pressurefluid distributed by the valve 4-1 enters` the valve chamber 45 through a supply passage51l in the transverse plane of the space between the anges 48 and 49'and passes over the peripheral surfaces of the iianges to the passages 53 and 54. Annular grooves 58 and 59 encircling the anges 48 and 49 provide the spaces necessary around the valve flanges for the pressure fluid flowing to the inlet passages.

Suitable means are provided to enable the movement of the valve 41 to be controlled with the hand grasping the bar or grip member 4|. To this en-d a plunger 6|) is disposed in the front end of the valve chamber 45 to act as a movable stop member for the valve. The plunger 60 is freely slidable in the valve chamber. Its rearward end surface 6| acts as a seat for the actuating surface 5l of the valve and in the plunger are a series of longitudinally extending passages 62 that open into an annular groove 63 adapted to register with the inlet passage 53.

During the inoperative period of the percussive tool the plunger 60 is held against the Valve 41 and the valve, in turn, is held against the shoulder 56 by a spring E4 arranged in the plug 46 and seating against the plunger. The opposite end of the plunger carries a stem 65 that extends sli-dably through the valve 41, to guide the valve, and the rearmost or free end 66 of the stem extends into a groove 61 in the grip member 4I to receive the thrust of a lever 68 mounted pivotally in the groove 61 on a pin 59.

In practice, and during the idle or non-operating position of the parts, the spring 64 presses the plunger 6U against the actuating surface-5l and maintains the actuating surface 52 seated against the shoulder 55, thus preventing admission of pressure fluid to either of the inlet passages 53 and 54. Y

Whenever it is desired to set the piston 21 in motion for actuating the wo-rking implement 29 the plunger 65 is depressed by pressure applied against the lever 68. In this way the valve 41 is released and will then reciprocate to distribute the pressure fluid to the inlet passages 53 and 54. More specically, in the position of the valve shown in Figure 1, pressure fluid ows from the supply passage 51 over the flange 49 and through the recess 55 and the inlet passage 54 into the rearward end of thepiston chamber to drive the piston 21 forwardly on its working stroke.

After the piston 21 reaches a position in which it covers the exhaust port 35 the air in 1the front end of the piston chamber will be compressed and forced through the passages 53, 63 and 62 against the actuating surface 5l and shift the valve rearwardly against the shoulder 56 t-o cut-off the admission of pressure fluid to the rearward end of the piston chamber. In the new position of the valve pressure uid flows over the valve flange 48 through the passages 62 and associated channels into the front end of the piston chamber to return the piston.

When, during its rearward stroke, Ithe piston covers the exhaust port 30 the ail` in the rearward end of the piston chamber 26 will be compressed and forced through the passage 54 and the recess 55 against the actuating surface 52 and return the valve 41 to its initial position.

I claim:

1. In a fluid actuated percussive tool, the combination of a casing having a piston chamber and a piston in the piston chamber, a v-alve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber to valve pressure fluid from supply to the inlet passages, a stationary stop means coooperating with the valve to prevent admission of pressure fluid to one inlet passage, and

a stop member in the valve chamber movable automatically in one direction for holding the valve against the stop means and to cooperate with the valve -to prevent the admission of pressure fluid into another inlet passage.

2. In a uid actuated percussive tool, the combination `of a casing having a piston chamber and a piston in the piston chamber, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve reciprocable in the valve chamber to valve pressure fluid from supply to the inlet passages, a stationary stop means cooperating with the valve to prevent admission of pressure fluid to one inlet passage, a stop member in the valve chamber movable automatically in one direction for holding the valve against the stop means and cooperating with the valve `to prevent the admission of pressure uid into another inlet passage, means for manually moving the stop member in an opposite direction, and means on the stop member to guide the valve.

3. In a fluid actuated percussive tool, the combination of a casing having a piston chamber and a piste-n in the piston chamber, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the pist-on chamber, a valve reciprocable in the valve chamber to valve pressure fluid from supply to the inlet passages, a stationary stop means in the valve chest cooperating with an end of the valve to prevent admission `of pressure fluid to one inlet passage, a manually movable spring-pressed stop member for controlling the movement of the valve, and a stem on the stop member extending through the valve for guiding said valve.

4. In a fluid actuated percussive tool, the combination of a casing having a piston chamber and a piston in the piston chamber, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber to effect the distribution of pressure uid to the inlet passages, manually operable spring-pressed means in the valve chamber for controlling the movement of the valve, and means on said manually operable means for guiding the valve.

5. In a fluid actuated percussive tool, the combination of a casing having a piston chamber and a piston in the piston chamber, a valve chest having a Valve chamber, inlet passages leading from the valve chamber to the piston chamber, ya reciprocatory valve in the valve chamber for controlling the distribution of pressure fluid to the inlet passages,l a manually operable springpressed plunger in the valve chamber to control the movement of the valve and having a passage to convey pressure fluid from the valve chamber to an inlet passage, a rod on the plunger extending through the valve to form a guide therefor, and manually operable means for shifting the plunger to a limiting position.

GEORG-E H. FUEHRER.

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