US2456325A

US2456325A - Pressure cylinder for hydraulic brakes

Info

Publication number: US2456325A
Application number: US547426A
Authority: US
Inventors: Albert E Roy
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-07-31
Filing date: 1944-07-31
Publication date: 1948-12-14
Anticipated expiration: 1965-12-14

Description

Dec. 14, 1948. ROY 2,456,325-

PRESSURE CYLINDER FOR HYDRAULIC BRAKES Filed July 31, 1944 19'. 5 INVENTOR.

LBERT 5. Roy;

fiatented Dec. 14, 194

OFFICE 2,456,325 PRESSURE CYLINDER FOR HYDRAULIC BRAK Albert E. Roy,Glendale, Calif.

Application July 31, 1944, Serial No. 547,426 11 Claims. (01. 60 54.6)

This invention relates to a pressure cylinder i for hydraulic brakes, such as are used on motor vehicles, and is a re-file of my former application,

'Serial No. 446,147, filed June 6, 1942, and now abandoned.

An object of my invention is to provide a novel pressure cylinder for hydraulic brakes, whereby the initial movement of an operating lever causes sufficient pressure to be transmitted to the pressure cylinders of the braking system to actuate a .brake shoe into initial contact with the braking surface of a brake drum, while further movement of the operating lever causes a high pressure to be applied to the brake cylinders for braking purposes.

Another object of my invention is to provide a novel pressure cylinder for hydraulic brakes in which the foot pressure against the operating lever will gradually increase as the brakes are set, thus providing a brake system in which the feel is the same as with hydraulic brakes now in general use.

Still another object of my invention is to provide a novel high-pressure cylinder for hydraulic A feature of my invention resides in the novel means of opening a valve and permiting liquid under pressure from the pipe lines to flow back into the primary cylinder when the pistons in the pressure cylinders are retracted.

Other objects, advantages and features of invention may appear from the accompanying drawing, the subjoined detailed description and the appended claims.

In the drawing:

Fig. 1 is a vertical sectional view of my pressure cylinder for hydraulic brakes and showing the pistons in retracted position, and

Fig. 2 is a side elevation of a modified form of pressure cylinder for hydraulic brakes with parts broken away to show interior construction.

Referring more particularly to the drawing, my pressure cylinder for hydraulic brakes comprises a primary cylinder I and a high-pressure cylinder 2, The high-pressure cylinder is smaller in diameter than the primary cylinder, and is arranged co-axially therewith. A liquid reservoir 3 is arranged above the primary cylinder I, and an inlet port 4 permits liquid to flow back and forth between the reservoir and the primary cylinder.

A primary piston 5 is slidably mounted in cylinder 1 and is provided with an annular packing ring 6 to prevent leakage past the piston. The piston 5 is of hollow cup-shaped formation and one-half itsnormal size, further force exerted defines a chamber I4 tubular hub or shank 9.

located within the piston and open at its outer end. A high-pressure piston l is slidably mounted in the high-pressure cylinder 2, and is provided with suitable annular packing 8 to prevent leakage. A tubular hub or shank 9 connects the pistons 5 and l and serves as a conduit through which liquid may flow from the chamber l4 to the high pressure cylinder.

A low-pressure piston H3- operates within the chamber I4 of the primary piston 5 and moves longitudinally of the, piston 5 under the urge of operating mechanism, such as the brake pedal. The push rod ll engages the low-pressure piston l0 and this push rod is actuated by the brake pedal in a usual and well-known manner. A hollow sleeve l2 extends forwardly from the lowpressure piston IE) and closely fits within the A port I3 is formed through the'wall of the sleeve and communicates with the inside of the chamber E4 of the primary piston 5, permitting liquid to pass from the lowpressure chamber M of piston 5 into the braking formed inthe inner end of the primary piston 5 to prevent fluid from being pushed back into the 'reservoir 3 when the low-pressure piston 5 is moved forwardly and the brakes are applied. A

coil spring .l in chamber l4 has one end bearing pressure piston Ill and urges this piston into its I released or retracted position, as shown in Fig. 1.

The high p-ressure piston l is formed with a central bore I8 extending entirely therethrough, and this bore is controlled by a ball valve 49. The ball valve is normally urged against its seat by the spring 20. A pipe 2| extends from the outer end retracted position. A trip finger 23 is pivotly mounted on the piston l and is adapted to engage and unseat the ball valve l9. action occurs when the drag rod 24 is pulled This unseating rearwardly on retraction of the low-pressure pistonlO. Thedrag rod 24 is pivotly attached at one -end'to the finger 23 and is slidably mounted through the spider 25 of the low-pressure piston Ill, The strength of spring is somewhat less than that of spring 22, thus permitting piston ID to move inwardly within chamber l4 upon the initialapplication of force through push rod ll. However the strength of spring I! is sufficient through rod H and piston 10 causes inward movement of hollow piston 5 and high pressure piston 1 against the action of spring 22. Move- .ment of high pressure piston I of course immedi- "cylinder, a

3 ately increases the pressure in cylinder 2 over that in chamber I4 and causes valve I9 to close.

The operation of my pressure cylinder, thus far described, is as follows: 011 the initial pressure of the brake pedal, the rod II will cause the lowpressure piston to move forwardly in chamber 14 of the piston 5. The valve 15 is then immediately closed. The liquid under some pressure in the chamber [4 passes through the port l-3, thence through the hollow hub or shank 9, past the ball check 1 9, and thence through the pipe M to the brake cylinders for initially filling the pipelines and also setting the brake shoes against the brake drums. As previously described further pressure against the rod Ill will cause the primary piston to be pushed forwardly and with it the high-pressure piston I. The necessary high pressure to actuate the brake mechanism is thus provided, and under these high-pressures the valve 19 will close. When the brake pedal is released, the low pressure piston H] is dragged rearwardiy, thus tripping the valve [9, through medium of the rod 24. Liquid can then fiowback to completely fill the chamber l4, ready for the necessary stroke of the pressure cylinder. If the chamber 14 is not entirely filled, the static pressure of liquid in the reservoir Swill open the valve l5, thus completely filling the chamber H1. The port 4 is open at all times, and consequently liquid from the reservoir will fill the primary cylinder ahead of the piston 5.

In Fig. 2, I have shown a slightly modified form of pressure cylinder for hydraulic brakes, including a primary cylinder 26, a high-pressure cylinder 21, and a primary piston 28, which is connected to the high-pressure piston by the hollow hub or shank 29. A low-pressure piston 30 is reciprocally mounted in the chamber of the hollow piston 28, the same as previously described. In this modification, however, the reservoir 3! is ftapped directly into the chamber of piston 28, through the flexible pipe 32 connected with the inlet of the chamber by a check valve 32-a which opens toward the chamber. An elongated slot 33 through whichfthe valve 32-0. passes permits the pipe 32 to move back and forth, as the piston 28 reciprocates. The balance of the structure is the same as previously described. The operation of the modified form of pressure cylinder is the same as previously described.

I claim:

l. A pressure "cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder supplied therefrom, a high-pressure cylinder arranged co-axially with the primary cylinder and being of smaller diameter "than the primary cylinder, a piston element extending through said primary cylinder and into said high-pressure cylinder and having a cup-shaped piston head ato'ne end operating in the primary cylinder amidefining a low pressure chambenand'a piston head at its other end operating in the high-pressure low-pressure piston reciprocally mounted in the chamber oi the piston head opcrating in the primary cylinder, means for actuating said low-pressure piston, said piston element having a passageway extending longitudinally therethrough from the chamber of the lowpressure piston to the high-pressure cylinder,

valve means controlling said passageway to permit fluid to pass from the low-pressure chamber to the high-pressure cylinder, during initial operation of the piston element on its compression stroke and preventin return flow of liquid from said high-pressure cylinder to said low-pressure 4 chamber during completion of its compression stroke, and valve-tripping means operatively connected to said low-pressure piston and adapted and arranged to tripsaid valve means on retraction of said low-pressure piston.

2. A pressure cylinder for hydraulic brakes comprising a primary cylinder, means for supplying liquid to said primary cylinder, a high-pressure cylinder co-axial with the primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of the piston element disposed within the primary cylinder and defining a chamber, a piston head on the other end of the piston element, disposed within the high-pressure cylinder, a low-pressure piston reciprocally mounted within the chamber of the first-named piston head, spring means in said hollow piston urging it inwardly and said low-pressure piston outwardly, means to actuate said low-pressure piston, said piston element having liquid passage extending longitudinally therethrough, from the chamber of the low-pressure piston to the highpressure cylinder, valve means controlling said fluid passage, and means operative upon retraction of said low pressure piston to open said valve means and permit fluid to return to said chamber.

3. A pressure cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder, an open port connecting the reservoir and the primary cylinder, a high-pressure cylinder coaxial with the primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of the piston element operating Within the primary cylinder and defining a chamber, a piston head on the other end of the piston element, operating within the high-pressure cylinder, a low-pressure piston reciprocally mounted within the chamber of the first-named piston head, spring means in said chamber bearing against the low-pressure piston and urging the same outwardly and bearing against the forward Wall of said hollow piston and urging the same inwardly, means to actuate said low-pressure pis- 'ton and force the same inwardly, said piston element having a liquid passage extending longitudinally therethrough from the chamber of the low-pressure piston to the high-pressure cylinder, valve means controlling said liquid passage, a second valvein the first-named piston head, closing on the compression movement of the lowpressure piston and opening on retraction of said low-pressure piston, and means for opening said "first valve upon retraction of said low pressure piston.

4. A pressure cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder, an o'p'en'port connecting the reservoir and the primary cylinder, a high-pressure cylinder coaxial with the primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of the piston element disposed within the primary cylinder and defining a chamber, a piston head on the other end of the Piston element, disposed within the high-pressure cylinder, a low-pressure piston reciprocally mounted within the chamber of the first-named piston head, spring means in said chamber bearing "against the low-pressure piston and urging the same outwardly, means to actuate said low-pressure piston, said piston element having liquid passage extending longitudinally therethrough, from the chamber of the low-pressure piston to the high-pressure cylinder, valve means controlling saidjliquid passage, and tripping means 'operatively connected to the low-pressure piston and engaging said valve means, whereby said valve means is released on retraction of the lowpressure piston.

5. A pressure cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder, an open port connecting the reservoir, and the primary cylinder, a high-pressure cylinder ooaxial with the primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of the piston element disposed within the primary cylinder and defining a chamber, a piston head on the other end of the piston element disposed within the high-pressure cylinder, a low-pressure piston reciprocally mounted within the chamber of the first-named piston head, spring means urging against the low-pressure piston toward a retracted position, means to actuate said low-pressure piston, said piston element having liquid passage extending longitudinally therethrough, from the low-pressure piston to the high-pressure cylinder, valve means controlling said liquid passage, tripping means operatively connected to the low-pressure piston and engaging said valve means, whereby said valve means is released on retraction of the low-pressure piston, and a second valve in the firstnamed piston head, closing on the compression movement of the low-pressure piston and opening on retraction of said low-pressure piston.

6. A pressure cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder supplied therefrom, a high pressure cylinder coaxial with said primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of said piston element disposed Within said primary cylinder and defining a chamber, a piston head on the other end of said piston element disposed within said high-pressure cylinder, a low-pressure piston reciprocally mounted within said chamber, means for actuating said low-pressure piston, said piston element having a liquid passage extending longitudinally therethrough from said chamber to said high-pressure cylinder, valve means controlling said passage, and tripping means operatively connected to said low-pressure piston and adapted to trip said valve means on retraction of said low-pressure piston.

7. A pressure cylinder for hydraulic brakes comprising a liquid reservoir, a primary cylinder supplied therefrom, a high pressure cylinder coaxial with said primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of said piston element disposed Within said primary cylinder and defining a chamber, a piston head on the other end of said piston element disposed within said high-pressure cylinder, a low-pressure piston reciprocally mounted Within said chamber, means for actuating said low-pressure piston, said piston element having a liquid passage extending longitudinally therethrough from said chamber to said high-pressure cylinder, valve means controlling said passage, and means operative upon retraction of said low pressure piston to open said valve and permit fluid to return to said chamber.

8. A pressure cylinder for hydraulic brakes comprising a primary cylinder, a high pressure cylinder coaxial with said primary cylinder, a piston element common to both cylinders, a hollow piston head on one end of said piston element disposed within said primary cylinder and defining a chamber, a piston head on the other end of said piston element disposed within said high-pressure cylinder, a low-pressure piston reciprocally mounted within said chamber, means for actuating said low-pressure piston, said piston element having a liquid passage extending longitudinally therethrough from said chamber to said high-pressure cylinder, valve means controlling said passage, and means operative upon retraction of said low-pressure piston to open said valve and permit fluid to return to said chamber.

9. A pressure cylinder. for hydraulic brakes comprising a primary cylinder of relatively large diameter, a high-pressure cylinder of less diameter coaxial with said primary cylinder, a piston element common to both cylinders having a piston head on the end thereof in said high-pressure cylinder, a low-pressure piston reciprocally mounted in said primary cylinder having an inner portion slidable within said common piston element, means for actuating said low-pressure piston, said piston element having a liquid pass- Number 10. A pressure cylinder for hydraulic brakes comprising a primary cylinder of relatively large diameter, a high-pressure cylinder of less diameter coaxial with said primary cylinder, a piston element common to both cylinders having a piston head on the end thereof in said highpressure cylinder, a low-pressure piston reciprocally mounted in said primary cylinder, means for actuating said low-pressure piston, said piston element having a liquid passage extending longitudinally therethrough from said primary cylinder to said high-pressure cylinder, valve means controlling said passage, and means operative upon retraction of said low-pressure piston to open said valve and permit fluid to return to said primary cylinder.

11. A pressure cylinder for hydraulic brakes comprising a primary cylinder of relatively large diameter, a high-pressure cylinder of less diameter coaxial with said primary cylinder, a piston element common to both cylinders having a piston head on the end thereof in said highpressure cylinder, a low-pressure piston reciprocally mounted in said primary cylinder, means for actuating said low-pressure piston, said piston element having a liquid passage extending longitudinally therethrough from said primary cylinder to said high-pressure cylinder, valve means controlling said passage, and valve tripping means operative by retraction of said low pressure piston to open said valve and permit fluid to return to said primary cylinder.

ALBERT E. ROY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Leuschner Nov. 26, 1935 FOREIGN PATENTS Country Date France Nov. 11, 1935 Number