US1921008A - Pump for hydraulic systems - Google Patents

Description

Aug. 8, 1933. B sl-HNN 1,921,008

PUMP FOR HYDRAULIC SYSTEMS Filed April 17, 1929 4 Sheets-Sheet l INVENTOR Aug. 8, 1933. B, sHlNN 1,921,008

PUMP FOR HYDRAULIC SYSTEMS Filed April 17, 1929 4 Sheets-Sheet 2 INVENTOR WITNESS: ATTORNEY Aug. 8, 1933. B. H. SHINN 1,921,008

PUMP FOR HYDRAULIC SYSTEMS Filed April 17, 1929 4 Sheets-Sheet 3 1 M O Y; w 6

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O BY WITNESS2 ATTORNEY Aug. 8, 1933. H, s N 1,921,008

PUMP FOR HYDRAULIC SYSTEMS Filed April 17, 1929 4 Sheets-Sheet 4 Patented Aug. 8, 1933 PUMP FOR HYDRAULIC SYSTEMS Byron H. Shinn, Washington, Pa., assignor to Shinn Devices Corporation, Washington, Pin, a Corporation of Delaware Application April 17, 1929. Serial No. 355,852

6 Claims. (Cl. sip-54.6)

This invention relates to a pump for hydraulic systems, the general object of the invention being to provide the pump with a large and a small cylinder, with a piston in each cylinder and to so construct and arrange the parts and the operating means for the pistons that upon the initial movement of the operating means, the large piston will be caused to displace a large volume of the fluid into the system, there- 10 by quickly moving the actuated member into contact with another member, after which the small piston is automatically brought into action to highly compress the fluid and thereby cause the fluid to complete the movement of the actuated member with great force.

Another object of the invention is to provide means for adjusting the operating means whereby, the movements of the pistons can be regulated so that the volume of fluid displaced by the large piston can be varied and the pressure exerted on the fluid by the small piston can also be varied.

Another object of the invention is to provide means whereby the system is in communication with the supply tank when the pistons are in inoperative position so that temperature changes will not vary the volume of liquid in the system and ,air is allowed to escape from the system. This arrangement also automatically keeps the system filled with fluid.

Another object of the invention is to provide a safety device which will allow the large piston to compress the fluid if the small piston should fail to properly function.

7 When this invention is used with a hydraulic brake system, it will give optional pedal pressure regardless of how big and heavy the automobile, truck or bus is upon which it is used and it gives optional travel for releasing and applying the brake shoes or bands, thereby making it possible to give the shoes or bands great clearance and eliminating any adjusting for the life of the lining. It also eliminates dragging and locking of the brakes due to close clearance and it eliminates lack of pedal travel due to air or leaks in the system and the building up of pressure in the system due to a rise in the temperature of the fluid.

When the invention is used on a hydraulic jack, it eliminates waste of time and efiort in raising the jack to the load as it gives a quick lift up to the point of taking the load and then automatically takes up the load at leverage increased to any desirable degree. The lifting head of the jack can be moved up to the load and in which:--

Figural is a sectional view, with parts in elevation, showing one form of the invention.

Figure 2 is a section on line 2-2 of Figure 1. Figures 3, s and -5 are diagrammatic views showing the parts in difierent positions.

Figure 6 is a sectional view, with parts in elevation, showing a modification.

Figures 7, 8 and 9 are diagrammatic views of J the modification, showing the parts in diflerent positions.

Figure 10 is a sectional view with parts in elevation, showing the invention used on a hydraulic jack.

Figure ii is a detail view showing the check valve in the outlet from the two-way valve.

Figure 12 is a sectional detail view showing the connections between the reservoir and the small and large cylinders.

Figure 13 is a sectional view showing a modifled form of two-way valve.

Figure 14 is a section on line 14-14 of Figure Figure 15 is a section on line 1515 of'Figure 13. l

Figure 16 is a section on line 16 16 of Figure 13.

Referring to the first form of the invention, the numeral 1 indicates a large cylinder and 2 a small cylinder. The two cylinders are connected together by a passage 3 and a by-pass 4 connects one end of the cylinder 1 with the cylinder 2, this passage containing a check valve 5. A pipe 6 connects the cylinder 1 with an elevated supply tank and the cylinder 2 is connected by the pipes 7 with the front and rear brakes. A large piston 8 is arranged in the cylinder 1 and a small piston 9 is arranged in the cylinder 2 and when these pistons are in inoperative position, the pipe 6 will be communieating with the cylinder 1 and the passage 3 will be in communication with the cylinder 2. A

telescopic connecting rod 10 connects the piston 8 with one end of a lever 11 and a rod 12 connects the small piston 9 with the other end of the lever. A link 13 is pivotally connected with the center of the lever and with the depending part of a pedal 14 which is pivoted at 15. The connecting rod 10 is attached to the piston 8 by a ball and socket joint 16 and a spring 17 is placed on the connecting rod 12 and bears against the cylinder 2 and against a nut 18 adjustably mounted on the rod. A dust cap 19 covers the rear end of the cylinder 1 and is suitably attached to the connecting rod.

From the foregoing it will be seen that with the pistons in the postion shown in Figures .1 and 3, the system will be filled with fluid from the supply tank and when the pedal is depressed to apply the brakes, the spring 1'7 will prevent movement of the rod 12 so that the lever 11 will pivot about its point of connection with said rod 12 and-thus the large piston 8 will be moved toward the closed end of the cylinder; and this movement will force the fluid in the large cylinder through the pasage 3 and the by-pass 5 into the cylinder 2 and from this cylinder, the fluid will pass through the pipes to the brake cylinders so that the shoes or bands will be quickly moved against the drums, due to the large volume of the fluid moved by the large piston. As soon as the pressure of the fluid becomes greater than the tension of the spring 1'7, the lever 11 will pivot about its point of connection with the rod 10 so that the piston 9 will be moved forwardly and during the first part of the movement, the passage 3 is closed, thus locking the large piston and applying great pressure to the fluid so that the bands or shoes are applied with great force to the drums. When the foot is removed from the pedal, the spring 1'7 and pressure in the system will return the small piston to its normal position and then as the passage 3 is uncovered the fluid will pass into the large cylinder and pressure thereof will return the large piston to its normal position. The telescopic connection will permit sudden release of the pedal to occur without returningthe large piston more rapidly than the return flow. With a rigid connection a too rapid return of the piston would .occur. Thus the quick initial movement of the bands or shoes enables the same to be set with great clearance in relation to the drums, as the bands will be quickly moved against the drums by the large volume of fluid moved by the large piston and then the flnal pressure is exerted on the bands by the action of the small piston on the fluid. By having the system in communication with the supply tank when the pistons are in inoperative position, the system is automatically kept filled from the supply tank and temperature changes acting on the fluid are automatically taken care of.

moves the necessity of frequent adjustments of the brake mechanisms as is necessary where the bands are set with very close clearance. By adjusting the tension of the spring .17, the final pressure exerted by the small piston, the volume displaced by the large piston,.-the point at which the small piston starts operation and the amount of pedal movement can be varied. By providing the by-pass 4 and the check valve 5, if the small piston should move prematurely and cover the passage 3, the large piston would Any air in the system will also escape into the supply tank. This invention reforce the fluid past the check valve and through the by-pass and thus operate the brakes.

Figure 3 shows the parts with the pistons in inoperative position.

Figure 4 shows the large piston at about the end of its movement, with the small piston about to come into operation, and Figure 5 shows the small piston at the end of its forward stroke.

In the modification shown in Figures 6, '7, 8 and 9, the cylinders 1 and 2' are connected by the pipes 3 and 3" with the valve casing 20. Partitions 21 and 22 are arranged in the valve casing and divide the same into upper and lower chambers, the upper chamber being in communication with the large cylinder and the lower chamber with the small cylinder. A valve seat is arranged in each partition and these seats are engaged by a two-way valve 24, the stem of which is connected with a curved flexible tube 25 which is in communication with the outlet 26 'of the casing. A leaf spring 2'7 is attached to an arm 28 formed on the cylinder 1' and this spring is connected with the upper end of the valve stem and the tension of this spring can be adjusted by the set screw 29.

Thus upon the initial movement of the operating means, the large piston is moved so that the fluid from the large cylinder will pass through the upper pipe 3' into the upper chamber and through the upper valve seat into the between the upper chamber and-said exhaust passage. This will bring the small piston into 1 5 action so that the fluid will be greatly compressed, as before described. By regulating the tension of the spring 2'7 by the set screw 29, the point at which the valve will be raised by the pressure acting on the tube 25 can be regulated so as to make the parts come into operation at any desired time.

Figures '7, 8 and 9 show the various positions of the parts during the operation of the device.

Figure 10 shows the invention used with a hydraulic jack. The arrangement of the parts is similar to that just described and illustrated in Figures 6, '7, 8 and 9, with the exception that the reservoir 30 is connected by a pipe 31 with a pipe 32 with which the outlet passage 26 of the two-way valve 24 is connected and this pipe 32 leads the fluid into the cylinder 33 of the jack so that the piston 34 in the cylinder 33 will operate the carriage 35 by means of the rod 36 and cause the wedge part of the carriage to lift the beam 3'7 through means of the roller 38, this beam carrying the shoe 39 for engaging the object to be lifted. Thus the great volume displacement of the fluid by the large piston will cause said fluid to quickly move the piston 34 forwardly to cause the carriage to swing the beam upwardly until the shoe engages the object to be lifted. Then the resistance offered by the object will prevent further movement of the cause the same to raise the beam to lift the object. As before stated, the. initialmovement can be made by one stroke of the jack handle and then a pumping action of the handle will cause the small piston to act on the fluid and lift the load.

A check valve 40 is placed in the outlet 26 from the two-way valve and a hand operated valve 41 is placed in the pipe 31. Thus by closing the valve 41 when the device is being used, the fluid pumped into the cylinder 33 will be trapped therein, as it cannot pass the check valve 40 so that the Jack will remainin operative position until the valve 41 is opened, when the fluid will flow from the cylinder 33 back into the reservoir: The small cylinder is connected with the reservoir by a pipe 42 and a pipe 43 connects the reservior with the large cylinder. These pipes contain the check valves 44. Thus both the cylinders are in communication with the reservior, as in the other forms of the device so that the system will always be kept full of fluid even though leakage occurs and air can escape from the system into the reservoir, due to the reservior being arranged at an elevation. Any air that gets into the system will rise in pipes 42 and 43 and accumulate below valves 44, and will escape upwardly through said valves whenever they open, as they do occasionally, to replenish oil in the system.

As will be understood, every time the large piston is drawn back, the large cylinder fills from the supply tank and then when the piston is forced ahead, the large cylinder volume is displaced through a two-way valve past the check valve into the operating cylinder 33. The check valve 44 prevents the fluid from returning to the reservoir from the large cylinder. This cycle is repeated until pressure in the operatingway valve and the check valve 40 in the operating cylinder 33. This cycle is also repeated as many times asnecessary to lift the load on th jack head to the desired height.

A second by-pass 45, containing an adjustable check valve 46, is used to connect the large cylinder with the small cylinder in bothforrns of the invention shown in Figures 1 and 6, so as to prevent the brakes being applied with too great a pressure as the spring of the check valve will be so adjusted that the valve will open to release the pressure to cylinder 1 just before the pressure becomes great enough to bring piston 9 into play and thus lock the brakes.

Figures 13, 14, 15 and 16 show another form of two-way valve which may be used in place of the two-way valve shown in Figures 6 and 10. Referring to these figures, the numeral 47 indicates a casing which is provided with a centrally arranged outlet 48, a lower inlet 49 and an upper inlet 50. Valve seats 52 and 51 are arranged in the cylinder above and below the outlet, and an extension 53 is detachably connected with the upper end of the cylinder. The lower part of the extension contains a piston 54 which is held in either one of two positions by the spring detent 55 engaging either sion, one end bearing against the piston and its a other end against a plug 59 threaded into the upper end of the extension. This plug provides means for adjusting the tension of the spring and it is formed with a depending part 60 .for limiting the upward movement of the piston. A rod 61 hasits upper end threaded and located within the piston which is made hollow and a nut 62 is threaded to the upper end of the rod and is located in the piston. Upper and lower springs 63 tend to hold the'nut in a central position relative to the piston. This rod extends within the cylinder 47 and has a stop 64 connected therewith which is located above they seat 52. A valve 65 is slidably arranged on the rod and has the upper end of its reduced part contacting the stop. A tubular stem 66 is slidably arranged on the lower part of the stem, the upper end of the stem being rounded to form a valve 6'7 which engages a seat formed on the bottom of the valve 65. The lower end of the stem 66 has a valve 68 formed thereon for engaging the seat 51 and a coil spring 69 encircles the stem .66 and bears against the valve 65 and the valve 68. A head 70 is formed on the lower end of the rod 61 and is slidably arranged in the lower part of the stem 66.

Thus with the parts arranged as shown in Figure 13, the valve 65 is held off the seat 52 by the stop 64 on the rod 61 and the spring 69 holds the valve 68 on the seat 51 and the valve 67 engages its seat'on the valve 65, this valve 67 preventing leakage around the stem. When the large piston moves forwardly, the liquid displaced thereby will flow through the inlet 50,

past the valve seat 52 and escape from the cylinder 47 through the outlet 48 to the brake system. This volume of liquid will take up all slack and clearances in the brake system and brake, re lease springs. When the pressure rises in the system to a predetermined point, the pressure under the piston 54 will cause the piston to move upwardly until the detent engages the lower groove 56, when further movement of the piston is ceased. As the stop 64 moves upwardly with the piston and the rod '61, the spring 69 will cause the valve 65 to follow the stop until the valve 65 seats itself on the seat 52. Thus the low pressure cylinder will be closed to the outlet 46, but the spring 69 will hold the valve 68 on its seat 51, thus closing communication between the small or high pressure cylinder and outlet 48 until the piston 54 passes its center position or has completed the first half of its movement. At this particular instant, the piston has traveled one-half of its total stroke. On the second half of the pistons upward travel, the head 70 engages the shoulder of the stem 66 above it so that the stem is caused to move with the head and thus the valve 68 is raised off its seat 51,

" valve 65 becomes low enough to permit the spring 58 to overcome the detent and thus the springwill force the piston downwardly until thedetent engages the upper groove. piston travels downwardly on the first half. of its movement, the spring 69 will seat the valve 68, thus closing the high pressure cylinder, but at the same time the valve 65 is held on its seat. After the piston has completed half of its downward movement, the stop 64 will strike the upper part of the valve65, forcing it fromits seat and compressing the spring 69 until the valve 65 again touches the valve 67, which prevents leakage around the stem. Then thelow pressure cylinder is in communication with the brake system. The adjustment of trip pressure is secured by varying compression or the detent spring and the compression of the spring 58.

It is thought from. the foregoing description that the advantages and novel features of the invention will be readily apparent.

It is to be understood that changes may be made in the construction and in the combination and arrangement of the several parts, provided that such changes fall within the scope of the appended claims.

What I claim is:-- l

1. A pump for a hydraulic system comprising a" large cylinder and a small cylinder, a piston in each cylinder, a lever, rods connecting the ends of the lever with the pistons, an actuating "member connected with the central part of the lever, an elevated supply tank in communication with both cylinders when the pistons thereof are in inoperative position, valve means for normally connecting the large cylinder of the system and closing communication of the small cylinder with the system and adjustable means operated by the pressure in the system for reversing the valve when the pressure reaches a predetermined point.

2. A pump for a hydraulic system comprising a large cylinder and a small cylinder, .9. piston in each cylinder, a lever, rods connecting the ends of the lever with the pistons, an actuating member connected with the central part of the lever, an elevated supply tank in communication with both cylinders when the pistons thereof are in inoperative position, valve means for normally connecting the large cylinder with the system and closing communication of the small cylinder with the system, adjustable means operated by the pressure in the system for reversing the valve when the pressure reaches a. predetermined point and adjustablemeans for connecting the small cylinder with the large cylinder when the pressure in the system reaches a second predetermined point higher than the 3. In a hydraulic brakingsystem, the combi- As the nation of a high pressure piston, alow pressure piston, piston rods for the respective ,pistons, cylinders for the pistons arranged side by side, the pistons being adapted to move in the same direction in their cylinders during their power strokes, pipe means to which fluid pushed by the pistons is delivered, an actuating equalizer bar operatively connected to both piston rods, and means responsive solely to the fluid pressure in the system which, at low pressures, holds the high pressure piston substantially stationary, and allows itto move only whena predetermined pressure has been reached.

4. In a hydraulic braking system, thecombim' .ation of a high pressure piston, a low pressure piston, high and low pressure'cylinders for the respective pistons, piston rods for the pistons, an actuating equalizer bar operatively connected to both piston rods, pipe means to which fluid from the two pistons is delivered and valve means responsive solely to the fluid pressure in the system which at low pressures puts the low pressure cylinder in communication with the pipe and shuts off the high pressure cylinder, and which at higher pressures, puts the high pressure cylinder in communication with the pipe and shuts oil the low pressure cylinder.

' 5. In a hydraulic braking system, theicombination of a high pressure piston, a low pressure piston,-high and low pressure cylinders for the respective pistons, piston rods for the pistons,

an equalizer bar operatively connected with the two piston rods, pipe means to. which fluid from the two pistons is delivered and valve means responsive to the pressure in said pipe'means which at low pressures puts the low pressure cylinder in communication with the pipe and shuts oi! the high pressure cylinder, and which at higher pressures, puts the high pressure cylinder in communication with the pipe and shuts off the low pressure cylinder.

6. Ina hydraulic braking system, the combination of a high pressure piston, a low pressure piston, piston rods for the respective pistons, high and low pressure cylinders for the respective pistons, arranged side by side, the pistons being adapted to move in the same direction in their respective cylinders on their power strokes a. pipe to which fluid Irom'the cylinders is delivered, an equalizer bar connected to the, two piston rods, and. valve means responsive to the pressure in said pipe which, at low pressures, puts the low pressure cylinder in communication with the pipe, and which, when a predetermined pressure is attained in the pipe, shuts oif the low pressure cylinder and puts the higher pressure cylinder is communication with the pipe.

BYRON H. SHINN.

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