US2112356A

US2112356A - Fluid pressure producing device

Info

Publication number: US2112356A
Application number: US54507A
Authority: US
Inventors: Clarence H Bock
Original assignee: Hydraulic Brake Co
Current assignee: Hydraulic Brake Co
Priority date: 1935-12-14
Filing date: 1935-12-14
Publication date: 1938-03-29
Anticipated expiration: 1955-03-29

Description

Patented Mar. 29, 1938 u y UNITED STATES PATENT OFFICE PRESSURE PRODUCING DEVICE Clarence H. Bock, Detroit, Mich., assignor to i `Hydraulic Brake Company, Detroit, Mich., a

corporation of California Application December 14, 1935, SerialNo. 54,507

5 Claims. (Cl. 60,-54.6)

This invention relates t fluid pressure` brake yviding a communication between the cylinder and l systems and more particularly to fluid pressure the chamber, and this port is controlled by a producing devices for such systems. valve mechanism housed in the chamber. The Heretofore in the construction of fluid pressure cylinder also has a discharge port 26 controlled producing devices havinga fluid reservoir, a cylby a two-way valve 28. 5

inder supplied therefrom, and a piston recip- As shown, the valve mechanism for controlling rocable in the cylinder,` the cylinder has generally the port 24 includes a double diametral'piston 3D been supplied with two ports providing commureciprocable in the chamber I8 and a hollow plug nications between the cylinder and the reservoir. 32 threaded in the open end of the chamber hav- 10 These ports are generally known as the supply ing an aperture 34 providinga communication be- 10 port and the compensating port. The latter is tween the chamber and the reservoir IIJ. The located slightly in advance of a flexible cup seated plug 32 receives the small end of the piston, and on the head of the piston when the piston is in a set screw 36 in the wall of the plug limits the retracted position. Hence, when the piston is movement of the piston.

moved on its compression stroke the pressure The piston has oppositely disposed heads 38 15 created in thecylinder forces the wall of the cup and 40 and a projection 42 on the head 40 havinto the port and this results in serious injury to ing a frusto-conical end 44 adapted to seat `in the cup. The present invention aims to overthe aperture 34 in the plug 32. The body of the come this objection. piston and the projection 42 are axially bored An object of the invention is to provide a comto provide a chamber 46 and a passage 48 com- 20 bined supply and compensating port for a uid municating with the chamber 46, and the passage pressure producing device. 48 communicates `with a diametral passage 50 in `Another object of the invention is to provide a the projection 42. u fluid pressure producing device including a res- A leak-proof cup 52 sleeved on the projection ervoir, a cylinder communicating therewith, a 42 and seated on the head 40 provides against 25 piston reciprocable in the cylinder, and means seepage of fluid past the piston, and a spring 54 for control of the communication betweenr the interposed between the plug 32 and the shoulder reservoir and the cylinder so that thel commuon the piston normally urges the piston toward nication functions as a combined supply and comthe bottom of the chamber I8 to move the frus- 0 pensating port. f tro-conical end 44 on the projection 42 from its 30 Other objects of the invention will appear from seat in the aperture 34 to establish communicathe following description taken in connection tion between the reservoir I Il and the cylinder with the drawing which form a part of this spec- 22.

ification, and in which,- The passage 48 is controlled by a ap valve 56 35 Fig. 1 is a schematic view of a uid pressure having a restricted opening 58. A spring 60 35 brake system embodying the invention; interposed between the valve 56 and a ring washer Fig. 2 is a vertical sectional View of the uid 62, pressed into the open end of the chamber 46, pressure producing device of the system snowing normally urges the valve 56 to its seat, and a the positions assumed by the parts while the sysleakproof cup 64 held on the head 38 of the pisi0 tem ls under pressure; and ton by a spring 66 provides against seepage of 40 Figure 3 is an enlarged view of the mechanism iluid past the piston. The valve 56 with its relnterposed between the compression cylinder and Stl'iCGed Opening 58 COOpSIaCeS in the Creation 0f the reservoir showing the parts in the positions suflicient pressure beneath the piston valve 3U assumed when the system is not under pressure. to close this valve against the resistance of the Referring to the drawing for more specific despring 54 when pressure is created in the cylin- 45 tails of the invention, IIJ represents a reservoir der 22. having a lling'cpening I2 which may be closed A fluid pressure delivery pipe or conduit 68 by a plug I4 having openings I6 for venting the suitably connected to the discharge port 26 has reservoir to the atmosphere. The reservoir has branches connected respectively to iiuid pressure a dependent sleeve or chamber I8 communicatactuated motors I0 arranged for the actuation of 50 ing therewith and vented to the atmosphere as brakes associated with the wheels of a motor indicated at 20, the purpose of which will herevehicle. 'I'he brakes may be of conventional type inafter appear. arranged in pairs, one pair for the front wheels Acylinder 22 formed normal to the base of the of the vehicle and the other pair for the rear` chamber I8 has a port 24 adjacent its head prowheels of the vehicle. 55

As shown, each of the brakes includes a fixed support or backing plate 12, a rotatable drum 14 associated therewith, a pair of corresponding interchangeable friction elements or shoes 18 pivoted on the backing plate, and a fluid pressure actuated motor corresponding to the motors 10 arranged on the backing plate and operative to move the shoes into engagement with the drum against the resistance of the retractile springs 18 connected between the shoes.

A piston 80, reciprocable in the cylinder 22, is retained in the cylinder by a washer 82 seated on an annular shoulder in the open end of the cylin' der and secured in'place by a retaining ring 84 seated in a groove in the wall of the cylinder. A leakprof cup 86 seated on the head of the piston is held against displacementby a spring 88 interposed between the cup and the two-way valve 28. T'his vspring also serves to return the piston to its retracted position." A recess in the back of the piston receives one end of a thrust pin 92 on the other end of which is a coupling 94 connected by a flexible boot 96 to the open end of the cylinder for the exclusionof dust and other foreign substances. The coupling 94 is connected by a rod 98 to a foot pedal lever |00 pivoted on a suitable support |02, and the lever is connected by a retractile spring |04 to a fixed support |06.

In operation, upon depressing the foot pedal lever |08 force is transmitted from this lever to the piston 88, resulting in moving the piston on its compression stroke. During the initial movement of the piston the fluid under pressure in the cylinder 22 and the chamber I8 causes actuation of the piston 30 resulting in closing the port 34 and thereby cutting olf communication between the cylinder 22 and the reservoir. Upon further movement of the piston on its compression stroke fluid is expelled from the cylinder 22 past the two-Way valve 28, which inhibits retrograde movement of the fluid, and through the fluid pressure delivery pipe 68 and its branches into the fluid pressure actuated motors 10, causing actuation of the motors with the resultant spreading of the shoes 16 into engagement with the drums against the resistance of the retractile springs 18.

Upon release of the foot pedal lever |00, this lever is returned to its normal position under the influence of the retractile spring |04. As the foot pedal lever moves to its retracted position, the thrust pin 92 connected thereto is retracted. This results in release of the piston 80, whereupon the spring 88 becomes effective to return the piston to its retracted position. Upon the initial movement of the piston on its retraction stroke, pressure on the piston 30 is released and the piston moves under the influence of the spring 54 to its retracted position, resulting in opening the port 34 and thus establishing communication between the cylinder 22 and the reservoir I0. Upon further movement of the piston on its retraction stroke, fluid is drawn from the reservoir through the passage 48 in the piston 30, past the valve 58 which moves downwardly to permit free flow of fluid from the reservoir to the cylinder 22, and through port 24 into the cylinder 22.

During ,this operation fluid is returning to the cylinder 22 from the motors 'l0 under the influence of the retractile springsv'l, and when the cylinder is filled any fluid in excess of the quantity required to completely lill the cylinder is returned through the port 58 in the valve 56, the

passage 48 in the piston, and the port I4 to the reservoir.

It will be observedl that should any expansionk or contraction of the fluid occur in the system due to changes in temperature, such expansion or contraction is readily compensated for by the flow of fluid through the port 58 in the valve 58.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. 'I'he 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. A fluid pressure producing device comprising a reservoir, a chamber communicating therewith, a cylinder communicating with the chamber, a

piston reciprocable in the cylinder, a piston valve reciprocable in the chamber and having a passage therethrough, a valve for control of the passage, said last mentioned valve having a restricted opening therethrough registering with said passage, said piston valve being normally positioned to provide communication between the cylinder and reservoir and being responsive to the increase of pressure in the cylinder upon advance of the piston to close such communication, and means for actuating the piston.

2. A iiuid pressure producing device compris- Ing a reservoir, a chamber communicating therewith, a cylinder communicating with the chamber, a piston reciprocable in the cylinder, a piston valve in the chamber for control of the communication between the reservoir and the chamber, said piston valve having a passage therethrough, said piston valve being normally positioned to provide communication between the 'reservoir and chamber but being responsive to the increase of pressure in the cylinder upon advance of the piston to close such communication, a spring pressed valve controlling the passage in the piston valve, said spring pressed valve having a restricted opening therethrough registering with said passage, and means for actuating the piston.

3. A iluid pressure producing device comprising a reservoir, a chamber communicating therewith, a cylinder having an inlet port providing communication between the chamber and the reservoir and a discharge port, a piston reciprocable ln the cylinder, a piston valve in the chamber for control of communication between the ,reservoir and chamber, said piston valve having l a passage therethrough, a spring pressed valve for control of the passage and having a compensating port, said piston valve being normally positioned to open said inlet port but being responsive to the increase of pressure in the cylinde upon advance of the piston to close ythe inlet port, and means for actuating the piston.

4. A fluid pressure producing device comprising a reservoir, a chamber communicating therewith, a cylinder having an inlet port providing communication between the chamber and the reservoir and an exhaust port, a piston reciprocable in the cylinder, a piston valve in the chamber for control of the communication between the reservoir and the chamber and having a passage therethrough, a spring normally retaining the piston valve in inlet port opening position, a spring pressed flap valve for control of the passage in the piston valve, said flap valve having a compensating port, said piston valve discharge port, a piston reciprocable in the cylbeing responsive to the increase of pressure in inder, a piston valve in the chamber for contml the cylinder upon advance of the piston to close of communication between the reservoir and the the inlet port, and means for actuating the pischamber and having a passage therethrough, a

5 to spring-pressed flap valve for control of the pas- 5 5.` A iluid pressure producing device comprissage and having a compensating port, said pising a reservoir, a chamber communicating thereton valve being normally in position to open said '11th. l cylinder having an inlet port providing a inlet port but being responsive to the increase of communication between the chamber and the pressure in the cylinder upon advance of the 10 reservoir and the discharge port, a two-way valve piston to close the inlet port, and means for ac- 10 for `control oi the discharge port. fluid pressure tuating the piston. actuating motors operatively connected to the CLARENCE H. BOCK.