US3460346A - Multi-step hydraulic power mechanism - Google Patents

Description

Aug- 12,1969 H. E. BRANSON 3,460,346

MULTI-STEP HYDRAULIC POWER MECHANISM Filed Oct. 5. 1967 f I" ff J 2 25 /21 o I 2 3,460,346 MULTI-STEP HYDRAULIC POWER MECHANISM Henry E. Branson, deceased, late of Lincolnwood, Ill., 'by Esther E. Branson, executrix, Lincolnwood, Ill., assignor to Stromberg Hydraulic Brake and Coupling Company, Chicago, Ill., a corporation of Illinois Filed Oct. 5, 1967, Ser. No. 674,699 Int. Cl. Fb 7/00, 7/08 U.S. Cl. 60-54.5 1 Claim ABSTRACT 0F THE DISCLOSURE A hydraulic cylinder contains a reciprocating piston which as it reciprocates forces hydraulic uid from the cylinder through a check valve to a hydraulically actuated element to cause a series of step by step movements thereof. A reservoir supplies hydraulic uid to the cylinder after each piston movement. The system includes means for forcing a return of the hydraulic fluid back through the cylinder to the reservoir when the check valve is opened.

SUMMARY OF THE INVENTION This invention relates to a hydraulic power mechanism. It has one object, to provide a power source which, under the control of the operator will, first, apply a series of hydraulic impulses to a closed hydraulic system, the impulses resulting in a step by step forward movement of a mechanical element. And second, it will provide means subject to the will of the operator to apply retrograde movement to the mechanical element and return the hydraulic uid to the power source.

The invention is, for convenience, illustrated as applied to a step by step automotive vehicle transmission, but may equally well be used for other purposes.

Other objects will appear from time to time throughout the specification and claim.

DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIGURE l is a view of the power source;

FIGURE 2 is a side elevation of FIGURE '1;

FIGURE 3 is a section along the line 3-3 of FIG- URE 3;

FIGURE 4 is a diagrammatic illustration of the hydraulically actuated mechanical element.

DESCRIPTION OF THE PREFERRED EMBODI- MENTS OF THE INVENTION Referring to FIGURES 1 and 2, the base 1 supports a cylinder 2. The latter carries a hydraulic fluid reservoir 3 which may be integral with or removable therefrom and may be filled through a filler cap 4. A fulcrum pin S supported in the flanges 6 projecting upwardly from the base 1 carries rotatably mounted thereon a sleeve 7 from which projects a lever arm 8 carrying a pedal `9. Sleeve 7 also carries a lever arm 10 to which is pivoted a piston rod 11 which penetrates the open end of the cylinder 2, being enclosed by an elastomeric bellows 12 to protect the open-ended cylinder 2 from dust and dirt.

A wall of the cylinder 2 is ported to communicate with the reservoir 3. The skirted piston 14 is slidable in the cylinder 2 and carries elastomeric packing sleeves 15 and 16 on each skirt, the piston rod 11 being loosely socketed in the recess 17 in the closed end of the piston. The piston is held within the cylinder at its outer skirt by snap ring or piston stop 18.

The piston is slotted at 19 in communication with the annular chamber 20 between the end skirts of the piston and the cylinder in communication with the makeup port Frice leading to the reservoir. A pin 21 is threaded in the wall of the cylinder to penetrate the slot 19. The slot permits movement of the piston longitudinally with respect to the pin 21. The piston 14 at its forward end is ported at 22 in communication with the slot 19. A ball valve 23 may be seated by valve spring 24. Return spring 25 biases the piston in upstream position toward the stop 18 as shown in FIGURE 3 to hold the ball valve 23I against the pin 21 to open the port 22.

The cylinder 2 is ported on the downstream side of the piston at 26 to communicate with the hydraulic duct 27 which leads to a check valve housing 28.

In the position shown in FIGURE 3, there is a free hydraulic fluid path from reservoir 3 through the make-up port, chamber 20, slot 19, port 22, to the downstream end of the cylinder, thence through the port 26 through duct 27 to the check valve housing 28.

When the pedal 9 is depressed, the lever 1()A rocks to move the piston rod 11 and the piston 14 to the left. This permits the valve spring 24 to seat the valve, closing the passage between the downstream end of the cylinder and the reservoir. Each separate rotation of the lever 8 compresses the return spring 25 and, because the valve 23 is seated, forces a slug of hydraulic fluid through the duct 27 into the check valve housing 28 and out through the duct 29. When the operator releases the pedal 9, the return spring 25 forces the piston back into the position shown in FIGURE 3 and, because check valve 28 inhibits hydraulic flow back through duct 27, a vacuum is created in the cylinder and draws make-up hydraulic fluid from the reservoir into the downstream portion of the cylinder to replace the slug previously discharged through the check valve. The capacity of the reservoir may vary, but it must always hold enough hydraulic uid to satisfy the number of strokes of the piston contemplated.

A suitable use for this device can well be a step by step automotive vehicle transmission.

The duct 29 leads to a slave cylinder 30 containing a piston 31, which drives through a rod 32, a rack 33, and when moved to the left compresses a return spring 34. Gear 35 meshes with the rack 32 and is mounted on a shaft 36 which is the control shaft of the automotive transmission.

Assuming that this is a tive step automotive transmission, each slug of hydraulic fluid forced into the cylinder 30 rotates the transmission shaft for one step. The check valve 28 locks the incompressible hydraulic fluid in the system to hold the transmission shaft in position. It cannot return and the spring 34 is strong enough to inhibit further forward movement of the rack. The next time the pedal is depressed, another slug of hydraulic fluid is forced through check valve 28 to move the transmission a step forward. This step by step operation continues until the last step is reached, at which time the spring 34 would bottom to serve as a stop to prevent further forward movement of rack 32.

When the operator wishes to return to the starting position, he pulls the control wire 37, with the cylinder in the position shown in FIGURE 3 and this rotates the lever 38 to unseat the check valve 28. The spring 33 biases the piston 30 in the return direction to force the hydraulic fluid back through the check valve and the cylinder through the valve 23 held open by the pin 21 into the reservoir.

The cylinder 2 is thus ported in register with the reservoir for intake and in register with duct 27 for exhaust under forward power operation of the piston. However, intake and exhaust functions of the ports are reversed when the spring 34 actuating the piston 31 forces the hydraulic fluid into the cylinder 2 through the piston 14 and out into the reservoir.

What is claimed is:

1. A power system including a manually actuated hydraulic master cylinder closed at one end and open at the other, containing a skirted piston, a piston stop in the outer end of the cylinder, a return spring biasing the piston against the stop, a piston rod, a manually actuated lever adapted to drive the piston away from the stop against the return spring to generate hydraulic pressure in the cylinder, the piston being longitudinally slotted and the end thereof nearest the return spring being ported in register with the slot, a valve biased to close the port, a pin projecting from the wall of the cylinder into the slot so positioned that it engages and unseats the valve when the piston is held against the stop, a make-up reservoir, a free hydraulic connection between it and the annular chamber defined by the skirts, the cylinder and the piston, the slot being open to said chamber, an outlet port leading from the return spring end of the cylinder, a slave cylinder, a duct between it and the outlet port, a manually releasable check valve in the duct biased to inhibit return of hydraulic fluid from the slave to the References Cited UNITED STATES PATENTS 2,649,692 8/1953 `Stelzer 60-54.6 2,817,955 .l2/1957 Mercier 60-545 2,847,827 8/ 1958 Johnson 60-54.6 3,204,413 9/1965 Pace 60-54.5 3,221,502 12/ 1965 Shellhausc 60-54.6

MARTIN P. SCHWADRON, Primary Examiner ROBERT R. BUNEVICH, Assistant Examiner U.S. Cl. X.R.

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