US2302109A - Vane type piston - Google Patents

Description

Nov. 17, 1942. H, M DODGE 2,302,109

VANE TYPE PISTON Filed May l5, 1940 \\n I4 Fi 9 3 /9 ,9 INVENTOR F1 7. E y How-ard M Dodge ATTORN EYS Patented Nov. 17, 1942 2,302,109 l vANE ma ns'roN Howard M. Dodge, Wabash, Ind., assignor to The General Tire Rubber Company, Akron, Ohio, a corporation of Ohio Application May 15, 1940, Serial No. 335,409

8 Claims.

This invention relates to vane type pistons for fluid pressure motors, and in particular to a novel piston construction for vacuum operated motors utilized in windshield wipers for vehicles.

It is an object of this'invention to provide a piston of the type mentioned in which an effective seal is provided between the piston and motor chamber wall but in which the contact area between the piston and motor chamber wall is considerably reduced to provide decreased Irictional engagement therebetween.

Another object is to provide a piston construction wherein the packing or seal-providing member is a single unit which may be readily applied to the piston.

A further object of the present invention is to provide a vane type piston which is simple in design and construction and which may be manufactured readily and inexpensively.

Other objects and advantages of the present invention will become apparent from the following detailed description accompanied by the drawing, in which like parts throughout the several views are indicated by the same reference numerals,

In the drawing:

Figure 1 is an elevational view with parts broken away illustrating the motor chamber with the piston mounted therein Fig. 2 is an enlarged elevational view in section of the piston showing details of its construction and assembly;

Fig. 3 is an enlarged fragmentary sectional view taken substantially on line 3 3 of Fig. 2, showing how the piston may be secured to its driving shaft;

Fig. 4 is an enlarged elevational view with partsl broken away illustrating further details of the piston construction;

Fig. 5 is an enlarged sectional view taken substantially on line 5 5 of Fig. 4, illustrating an improved packing member embodying the present invention; and

Fig. 6 is an enlarged sectional view taken substantially on line 66 of Fig. 4, illustrating another view of the packing member.

The fluid pressure motor chamber may best be seen in Fig. 1 and comprises a semi-cylindrical chamber I having a casing orwall 2 to which is connected a cover member 3 having formed therein a second semi-cylindrical chamber 4 which is concentric with the chamber I. The member 3 may be secured to the wall 2 in any piston. indicated generally by the numeral 6, is pivotally mounted intermediate its ends to a shaft "I, the axis of rotation of the shaft coinciding with the axes of the chambers I and 4.

In operation fluid pressure is alternately applied to opposite sides of the piston by any suitable means (not shown) to give it oscillatory movement used for driving a windshield wiper or the like which may be connected to the shaft 1. The piston proper comprises a flat body which includes a pair of rigid members or plates 8 disposed on opposite sides of the shaft 'l and provided with peripheral flange portions 9 which are directed toward the opposite plate to give the plates a somewhat cup-shaped appearance. To facilitate proper location of the plates with respect to the shaft and to aid in securing them thereto, the plates may be formed with arcuate portions I0 which are apertured to receive a suitable pin or rivet II. To insure that the plates are secured against movement and held in generally parallel positions, the plates are apertured at another location to receive a second pin II which passes through the plates and through an apertured spacing member I2 shown in Fig. 2.

To envelop the plates, and particularly their rim portions, a packing member or envelope I3, which is preferably constructed from a single piece of resilient material such as 'a rubber compound, synthetic rubber, etc., is provided The member I3 is provided with sealing surface portions Il at its outer periphery which converge beyond the periphery of the plates 8 to a crest I5, the crest being disposed approximately midway between the planes of the plates and outwardly of the space between the flanges 9 of the' plates 8. Since the sealing portions extending from both plates are integral and meet at crest I5, such sealing portion provides a yieldable engagement with the motor chamber wall and is adapted to be depressible into the space between the plates 8.

To provide a tight seal around the shaft where it emerges from the sides of the piston, the flanges 9 at the side portions of the plates 8 may be recessed as indicated at the numeral I6, and the sealing portions I 4 are also recessed in this region. Thus, when the piston is inserted into the motor chamber, the crest I 5 of the sealing portion may be slightly depressed so that the suitable manner such as by bolts 5. A vane-type regions of the sealing portion around the shaft that the crest i5 of the sealing portions i4 protrudes slightly beyond the portions of the sealing portions which embrace the shaft when the piston is not in the motor chamber.

To seal. the opposite sides of the piston at the points where the pins or rivets il pass therethrough, the envelope I3 may be apertured and tightly held to the plate by washers Il which embrace the pins il. In this construction the plates may be assembled, the envelope disposed therearound, the rivets and washers inserted, and the rivets headed so that the washers slightly compress the sealing member. An alternate method of construction would be to secure the plates together by the pins and then dispose the envelope around the plates so that it will completely cover one side of the plate and pins. Since it is only essential that the periphery of the plates and one side of the plates through which the pins extend be covered, the envelope may be constructed with a large aperture I9 in the' middle of one of the sides of the plates. This reduces the amount of material necessary for constructing the envelope and also permits access to the connection between the pins and the plate.

An advantage of the present invention is the provision of a casing structure or packing member constructed in a single integral unit which may be molded or otherwise fabricated from a suitable material. When the envelope I3 is made of a suitable rubber compound or the like, it may be molded. In this case it is desirable that the parting line of the mold be disposed at a point not located at the crest i5 so that an even and converge between the planes of the plates but uniform crest may be provided. Such a mold y with a parting line disposed at one side of the the piston and motor chamber wall is materially decreased. Since the sealing portions are constructed of a resilient material, and further, since they are designed to flex or be depressed into the space between the plates although they are normally urgedtoward the motor chamber wall, a yieldable but positive seal is maintained. In the event that the envelope or packing member becomes worn by use, it will still maintain contact with the motor chamber wall because its action is to be urged thereagainst.

It is to be understood that variations and modifications of the speciiic devices herein shown and described for purposes of illustration, may be made without departing from the spirit of the present invention.

What I claim is:

1. A vane type piston for a uid pressure motor which comprises a pair of spaced plates, a shaft between said plates and adapted to be secured thereto, and an integral resilient packing member adapted to envelop the edge portions of the plates and to extend across the space between the edges of the plates, said member provided with `sealing portions extending peripherally around the piston beyond the edges of said plates f and depressible into the space between said plates.

2. In a vane type piston having a pair of spaced plates adapted to be secured to a rocker shaft on beyond the side edges of the plates to provide a relatively small area of contact with the motor chamber walls.

3. In a vane type piston having a pair of spaced plates adapted to be secured to a rocker shaft for pivotal oscillation in a fluid pressure motor chamber, an integral rim member surrounding the periphery of the plates and embracing the shaft where it emerges from between the plates, said rim member having sealing surface portions converging at the periphery of the rim to a crest disposed approximately midway between the plates and beyond the periphery thereof, whereby an approximate line contact may be had between the piston and the motor chamber walls to provide an effective seal between the opposite sides of the piston while decreasing the frictional engagement of the piston with the motor chamber walls.

4. In a vane type piston having a pair of spaced plates adapted to be secured to a rocker shaft for pivotal oscillation in a fluid pressure motor chamber, an integral rim member surrounding the periphery of the plates and embracing the shaft where it emerges from between the plates, said rim member having sealing surface portions converging at the periphery of the rim to a crest disposed approximately midway between the plates and beyond the periphery thereof, said crest being adapted to flex toward the space between said plates, whereby an approximate line contact may be had between the piston and the motor chamber walls to provide an effective seal between the opposite sides of the piston while decreasing the frictional engagement of the piston with the motor chamber walls.

5. A vane type piston pivotally mounted for oscillation in a iiuid pressure motor which comprises a pair of plates adapted to be secured to opposite sides of a rocker shaft, means for securing said plates in spaced relation at another location, an integral member enveloping the peripheral portions of the plates, primary sealing surface portions on said member converging at the periphery of the member to a crest disposed between the planes of the plates but beyond the peripheries thereof, and secondary sealing portions on said member to seal the piston in the region of the securing means.

6. A vane type piston comprising a substantially rigid fiat body having opposite sides terminating in spaced generally parallel peripheral confronting edge portions providing therebetween a substantially continuous recess about the body, and a single piece resilient envelope embracing both edges and extending over substantially the entire area of one side of the body, said envelope being unsupported between said edge portions 'of the body and having a narrow peripheral sealing crest disposed between the edge portions and yieldable by bodily movement of the envelope into the recess between said edges.

7. A vane type piston comprising a substantially rigid fiat body having opposite sides terminating in spaced generally parallel peripheral edges, and a single piece hollow sealing member formed of resilient deformable material, said member being of such shape and size when in unstressed condition as to receive the body internally thereof substantially without distortion and having in one side an opening adapted upon distension to pass the body in assembling the piston, the other side of the resilient member being of greater extent than said one side and substantiallycontinuous over an entire side of the body to seal the latter.

8. A one piece sealing member for a vane type piston comprising a hollow envelope structure of resilient molded rubber having generally fiat side walls one of which is formed with an opening adapted upon distension to pass a rigid piston body in assembling a piston and the other side wallof which is of greater extent than said one side wall and substantially continuous over an entire side of a piston body received in the hollow structure, said envelope member having integral edge and end walls connecting the sideV

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