US2679729A

US2679729A - Fluid pressure producing device

Info

Publication number: US2679729A
Application number: US64951A
Authority: US
Inventors: Harvey C Swift
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1948-12-13
Filing date: 1948-12-13
Publication date: 1954-06-01
Anticipated expiration: 1971-06-01

Description

Filed Dec. 13, 1948 K R M m w W H Z mm 4 W. m e 4 a Z .@w n a m 8 M %Q4 Q 5 9 4 "I. W 9 a W 4 V I! 8 A 6 4 4 8 0 6 7 Z 8 2 M HMS M 5 0 H 9 o 2 9 8 8 0 2 m a 6 3 3 w Patented June 1, 1954 FLUID PRESSURE PRGDUCING DEVICE Harvey C. Swift, Birmingham, Mich, assignor to Bendix Aviation Corporation, Detroit, Mich., a

corporation of Delaware Application December 13, 1948, Serial No. 64,951

2 Claims.

This invention relates to fluid pressure brake systems and in particular to fluid pressure producing devices for such systems.

Heretofore in the construction of fluid pressure producin devices having a fluid reservoir, a cylinder supply therefrom, and a piston reciprocable in the cylinder, the cylinder has generally been supplied with two ports providing communications between the cylinder and the reservoir. These ports are generally known in the art as a supply port and a compensating port. The latter is locked slightly in advance of a sealing cup seated on the head of the piston, when the piston is in a retractile position. Hence, when the piston is moved on its compression stroke the pressure created in the cylinder forces the wall of the cup into the compensating port and this results in serious injury to the cup. The instant invention aims to overcome the objection.

An object of the invention is to provide a fluid pressure producing device having but one intake port adapted to function both as a supply port and as a compensation port.

Another object of the invention is to provide a fluid pressure device including a reservoir, a cylinder supply therefrom, a piston movable in the cylinder and means for filtering the fluid as it passes from the reservoir to the cylinder.

Yet another object of the invention is to provide a fluid pressure device including a cylinder having a section of its wall made of porous material adapted to function as a supply port for the cylinder.

A further object of the invention is to provide a fluid pressure device including a reservoir, a cylinder supply therefrom having a section of porous material adapted to function as an intake port and also as a compensating port for cylinder.

Other objects and advantages of the invention will appear from the following description when taken in connection with the drawin forming a part of this specification, and in which;

Fig. l is a schematic View of a fluid pressure braking system embodying the invention, and

Fig. 2 is a vertical sectional view of the fluid pressure producing device of the system showing the piston of the device in retracted position.

Referring to the drawing for more specific details of the invention a single casting includes a reservoir it having a fillin opening l2 normally closed as by a hollow plug M provided with apertures It for venting the reservoir to the atmosphere, and a shield I B depended from the plug inhibits fluid from splashing through the apertures.

A. cylinder 20 depended from the bottom of the reservoir has a double diametral bore 22, the larger bore of the cylinder communicates directly with the reservoir and at the juncture of the bores is an internal shoulder 24. The free end of the cylinder is closed as by a head 26, and the head has diametrically disposed bosses 28 and 39 tapped to provide discharge ports 32 and as communicating with the smaller bore of the cylinder, and arranged at the juncture of the reservoir and the cylinder are

parallel bosses

36 and 38 tapped for the reception of fastening means, not shown.

A sleeve ll) extended upwardly from the bottom of the reservoir in coaxial relationship with the cylinder 20 has a bore 32 the diameter of which is greater than the diameter of the larger bore of the cylinder and this dilferential in bores provides a shoulder 44 at the juncture of the bottom of the reservoir and the sleeve. Spaced inlet ports 55 are arranged in the wall of the sleeve at the base thereof and in free end of the sleeve is a shoulder 48.

A porous sleeve 50 preferably of sintered metal is fltted in the sleeve 30. It completely covers the intake ports 45 and elfectively functions as a filter. The sleeve has an inner diameter commensurate with the diameter of the bore 22 of the cylinder 20. One end of the sleeve 56 seats on the shoulder 34, the other end thereof is aligned with the shoulder 48, and the sleeve is held against displacement by a washer 52 seated on the shoulder 68 and the sleeve 56, and secured in place by a retaining rin 55 seated in a groove in the wall of the cylinder.

A piston 55 reciprocable in the bore of the cylinder and the porous sleeve 59 has a recessed head 55, and a reduced body portion 60 providing in conjunction with the wall of the cylinder an annular chamber 62 communicating with the bore 22 of the cylinder by way of ports 64 in the head of the piston, and with the reservoir is by way of the inlet ports 56 and the porous sleeve 56, when the piston is in its retracted position. The piston also has a skirt 66 supporting a sealing cup and an axially disposed socket 79 extended well into the body of the piston.

A two-way valve 12 seated on the shoulder 24 in the cylinder 29 serves to control the flow of fluid and a spring 14 interposed between the valve and the head of the piston serves to retain the valve on the shoulder, and to return the piston to its retracted position.

The reservoir ID has an opening 16 in the top thereof immediately above the sleeve 40, and a flange I8 spaced from the perimeter defining the opening provides in conjunction with the top of the reservoir a shoulder 80.

A thrust pin 82 seated in the socket 19 of the piston has thereon a coupling 84. The thrust pin is embraced by a rubber diaphragm 86 secured on the shoulder 80 by a cup 88 fitted tightly in the sleeve 18. The cup has an axial opening for the reception of the thrust pin and a flange 99 on the cup 88 receives a flexible boot 92 connected to the coupling 84, and a rod 99 received by the coupling is pivotally connected to a foot pedal lever 96 pivoted on a suitable support 98 and connected by a retractile spring I99 to a fixed support I02.

Fluid pressure delivery pipes I94 and I96 con nected to the discharge ports 32 and a l of the cylinder 20 have branches connected respectively to fluid pressure actuated motors I98 preferably arranged in pairs; one pair for the actuation of brakes associated with the front wheels of a vahicle, and another pair for the actuation of brakes associated with the rear wheels of the vehicle.

The brakes are each of conventional type including a fixed support or backing plate HE], rotatable drum H2 associated therewith, a pair of friction elements or shoes H4 mounted on the backing plate and adapted to be actuated by a motor corresponding to the motors I98 for movement into engagement with the drum against the resistance of a retractile spring H6 connected between the shoes.

In operation, upon depressing the foot pedal lever 96 force is transmitted from the lever through the

linkage

82 and 94 to the piston 56, resulting in movement of the piston on its compression stroke. During an initial movement of the piston the sealing cups '68 covers the porous sleeve or member 50 thereby cutting off communication between the reservoir and the cylinder. Upon further movement of the piston on its compression stroke fluid is expelled from the cylinder past the two-way valve 24 which inhibits retrograde movement of the fluid, and through the fluid pressure delivery pipe 109 and I99 and the branches thereof into the fluid pressure actuated motors E98, causing actuation of the motors with the resulting movement of the shoes I I4 into engagement with the drums H2 against the resistance of the retractile springs H6 resulting in retarding the speed of the vehicle.

Upon release of the foot pedal lever 96 the lever is returned to its normal position under the influence of the retractile spring I90. As the foot pedal lever moves to its retractile position the .thrust pin 82 connected thereto is retracted.

This results in release of the piston 59 whereupon the spring 7 4 becomes efiective to return the piston to its retracted position. Upon the initial movement of the piston on its retracted position fluid is drawn from the reservoir through the ports 46 and the cintered sleeve member 59 into the cylinder.

During this operation fluid is returned to the cylinder 20 from the fluid pressure actuated motor 688. Under the influence of the retractile springs H5, and when the cylinder is filled, any fluid in excess of the quantity required to completely fill the cylinder is returned through the cintered sleeve or member 59 and the ports 48 to the reservoir. It is to be observed that should any expansion or contraction of the fluid in the system take place due to change in temperature, such expansion or contraction is readily compensated for by the flow of fluid through the ports 8 in the head of the piston into the annular chamber 62 thence through the cintered sleeve member 50 and intake ports 46 to the reservoir. It is also to be observed that the fluid flowing from the reservoir to the cylinder is completely filtered and that the fluid returning from the cylinder to the reservoir serves to cleanse the cintered material and/or filter.

Although this invention has been described in connection with certain specific embodiments the principles involved are susceptible to numerous other applications that will readily occur to per sons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention what I claim as new and desire to secure by Letters Patent, is:

1. In a fluid pressure producing device a reservoir, a cylinder depended therefrom, an annular flange on the bottom of the reservoir arranged concentrically to the cylinder and provided with spaced ports, a porous sleeve in the annular flange covering the ports and providing a continuation between the reservoir and the cylinder, a piston reciprocable in the cylinder and porous sleeve, means for moving the piston on its compression stroke and means for returning the piston to its retracted position.

2. In a fluid pressure producing device a reservoir, a cylinder depended therefrom, a fluid pressure system connected to the cylinder, a porous sleeve supported in the reservoir coaxially with respect to the cylinder and providing in effect a continuation thereof and an inlet therefor, a piston reciprocable in the cylinder and sleeve, a sealing cup on the piston adapted to uncover a substantial part of the porous sleeve when the piston is in its retracted position, means for moving the piston on its compression stroke and means for retracting the piston.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,175,447 Rike Oct. 10, 1939 2,245,991 Loweke June 17, 1941 2,294,351 White Aug. 25, 1942 2,358,887 Temple Sept. 26, 1944 2,373,745 Conway Apr. 17, 1945 2,447,142 Smith et al Aug. 17, 1948