US1943535A - Automatic cut-out safety device for hydraulic systems - Google Patents

Description

Jan. 16, 1934. I R. c. LAMOND 1,943,535

AUTOMATIC CUT-OUT SAFETY DEVICE FOR HYDRAULIC SYSTEMS I Filed March 31, 1931 2 Sheets-Sheet 1 Jan. 16, 1934. I R LAMOND 1,943,535

AUTOMATIC CUT-OUT SAFETY DEVICE FOR HYDRAULIC SYSTEMS Filed March 31, 1931 2 Sheets-Sheet 2 Patented Jan. 16, 1934 UNITED STATES PATENT OFFICE AUTOMATIC CUT-OUT SAFETY DEVICE FOR U HYDRAULIC SYSTEMS Application March 31,1931. Serial No. 526,749

6 Claims.

This invention relates to improvements in hydraulic apparatus, and more particularly in reciprocating fluid motors of the plunger type adaptable for use in steering mechanisms.

An object of the invention is to provide a motor of the stated type comprising novel means for limiting the travel of the plungers in their working strokes, thereby to prevent undesirable overtravel of the plungers and development of exl cessive pressures in the cylinders.

In its specific application to steering machines, an object of the invention is to provide novel means actuated by over-travel of the operating parts for bypassing the pressure in the working 1 cylinders of the motor to prevent damage to any part of the apparatus.

More particularly, the invention has for an object the provision of a plunger and cylinder assembly, constituting a reversible fluid motor, comprising means operative by a predetermined travel of the plungers in the cylinders for bypassing the actuating fiuid from thecylinders under pressure to those under suction, as hereinafter more fully set forth.

The invention further resides in certain mechanical details hereinafter described and illustrated in the attached drawings, in which:

Figure 1 is a plan view of a fluid motor having control means made in accordance with my invention;

Fig. 2 is an end elevation of the motor;

Fig. 3 is a vertical sectional view illustrating the details of the bypass valve;

Fig. 4 is a horizontal sectional view illustrating details of the control valve, and

Fig. 5 is areduced diagrammatic plan view illustrating application of the motor to a steering gear. I

- With reference to the drawings, a fluid motor -made in accordancewith my invention may cornprise a pair of plungers 1 and 2, the opposite ends of each of which are disposed in working cylinders numbered, respectively, 3, 4, 5 and 6. To the outer end of each of the cylinders is connected to pipe 7 through which fluid under pressure may be introduced to the said cylinders to actuate the plungers, or may be withdrawn therefrom as the direction of movement of the plungers may require. In a typical installation employing a motor of this character, the plungers 1 and 2 are adapted to move simultaneously in opposite directions, and suitable pumping apparatus forming no part of the present invention is provided to supply fluid pressure simultaneously to the two diagonally disposed cylinders 3-6 or 45, while the other pair of diagonally disposed cylinders are exhausted, whereby the desired opposite movements of the plungers 1 and 2 are accomplished.

In accordance with my present invention, I provide at each end of the assembly a bypass duct, 8 and 9 respectively, each bypass containing a valve ll, see Fig. 3, and a check valve 12. The valve 11, see Fig. 3, consists of a housing 13 containing a valve 14 of the poppet type, which 5 when seated, as illustrated, breaks communication between the opposite ends 01' the bypass ducts which connect respectively with the adja- I cent cylinders. A spring 15 is employed tending normally to hold the valve to its seat and funco tioning to insure a prompt re-seating of the valve 1 following elevation, as hereinafter set forth. The valve 14 has a stem 16 which carries at its lower end a piston 17 operating in a cylinder 18, the piston 17 having a greater effective pressure area 75 than the valve 14 for a purpose hereinafter set forth. The lower end of the cylinder 18 of the valve 11 associated with the duct 8 is connected through a pipe 19 with athree-way valve 21, this valve being also connected through a pipe 22 50 with the outer end of the cylinder 4. The valve 21, as shown in Fig. 4, has three ports, two of which are in communication with the pipes 19 and 22, while from the third port a pipe 23 extends to a suitable reservoir or leakage tank as- 35 sociated preferably with the fluid supply for the motor-actuating pumps (not shown). The valve 21 is of such character that in alternative positions it connects the pipe 19 with the pipe 22 and the pipe 23 respectively. Referring to Fig. 4, in which the valve is shown connecting the pipes 19 and 23, it will benoted that a 90 oscillation of the valve proper will result in a connection of the pipes 19 and 22 to the exclusion of the pipe 23.-

The cylinder 18 of the valve 11 of the bypass duct 9 is similarly connected through a pipe 24 with a three-way valve 25, this valve being identical with the valve 21 described above and comprising three ports, one of which communicates with the pipe 24, a second through a pipe 26 with 0 the outer end of the cylinder 3 and the third port connects through a suitable pipe with the afore-' said leakage tank. The valve 25 in alternative positions connects the pipe 24 with the pipe 26 and the pipe 24 with the said leakage tank to the exclusion ofthe pipe 26.

The plunger 2: is provided with a pair of projecting fingers 27 and 28, the finger 27 being adapted to ,engage projections 29 and 30 on the stem of the valve 21, see broken line position,

while the finger 28 is adapted to engage similar projections 31 and 32 on the stem of the valve 25. In the positions in which the valve is shown in Fig. 4, the said projections 29, 30, 31 and 32 are located as illustrated in Fig. 1. As the plunger 2 approaches the end of its travel in either direction, one or other of the fingers 2'7 and 28 respectively engages the projection 29 or 31 and shifts the associated valve element into position in which either the pipe 19 is connected with the pipe 22, or the pipe 24 with the pipe 26. With the plungers moving in the directions indicated by the arrows, the cylinders 4 and 5 necessarily are receiving fluid pressure from the source, while the cylinders 3 and 6 are being exhausted. Consequently, when the valve 21 is adjusted as described above to connect the pipe 19 with the pipe 22, fluid pressure from the cylinder 4 is exerted under the piston 17 of the valve 11 of the bypass 8, this pressure corresponding to the pressure exerted on top of the valve element 14 through the bypass connection between the upper portion of the valve chamber and the cylinder 4. As previously set forth, the piston 17 is of greater diameter than the face of the valve 14, and the pressure exerted through the pipe 24 is, therefore, suflicient to elevate the stem 16 and unseat the valve 14 against the opposing fluid pressure and the pressure of the spring 15. The

valve being opened, pressure is permitted to flow from the cylinder 4 directly to the cylinder 6, and since the cylinder 4 is connected with the cylinder 5, and the cylinder 6 with the cylinder 3, as previously set forth, a corresponding pressure equalization occurs in the cylinders 3 and 5, actuation of the plungers being immediately suspended. v

Upon reversal of the fluid pressure from the pumping apparatus, the cylinders 3 and 6 receive the pressure, while the cylinders 4 and 5 are connected with the suction. Equalization of the pressures in the cylinders through the bypass as previously described has resulted in an immediate return of the valve 14 to its seat through the action of the spring 15, and since bypassing of the pressure from the pressure to the exhaust cylinders is prevented by the check valves 12, the plungers are actuated in the reverse directions. The initial movement of the plunger 2 in this direction eflects a re-adjustment of the valve 21 to its original position through the action of the finger 2'7 upon the projection 30 whereby the cylinder 18 is again connected with the leakage tank. As the plunger 2 approaches the limit of its travel in the cylinder 5 and the plunger 1 in the cylinder 4, the finger 28 engages the finger 31 of the valve 25 which admits pressure to the valve 11 of the bypass 9 and opens the valve to permit bypassing of pressure from the cylinder 3 to the cylinder 5 with a consequent corresponding equalization of the pressures in the cylinders 4 and 6 and consequent immediate cessation of the plunger operation. An initial movement of the plunger 2 towards the cylinder 6 results in a re-seating of the valve 25 by engagement of the finger 28 with the projection 32 of the valve.

An application of the invention is illustrated in Fig. 5, wherein the plungers 1 and 2 are shown connected through rods 33 and 34 with the opposite ends of a yoke 35 attached to the rudder post 36 of a steering gear. The pipes 7 of the cylinders 4 and 5 are jointly connected through pipes 37 and 38 to one side of a reversible discharge pump 39; and the pipes 7 of the cylinders 3 and 6 are similarly connected through ipes 41 and 42 to the other side of said pump. Pressure is thus applied to one of these sets of cylinders simultaneously with an evacuation of the other set, and the pressure and evacuation may be reversed in the sets of cylinders by reversal of the pump discharge. The device described above positively precludes possibility of over-travel of the plungers 1 and 2 or of the rudder sufiicient to bring them into contact with the ends of the cylinders or with the hull of the vessel, and thereby prevents development of undue pressures which might result in damage either to the motor parts or to the rudder assembly.

There may be modification without departure from the invention.

I claim:

1. An hydraulic motor comprising a pair of parallel rams, and cylinders embracing the opposite ends of each of said rams, of means for connecting the diagonally opposite cylinders whereby pressure may be applied to one of said connected pairs simultaneously with exhausting the other pair of cylinders, a bypass connecting the pairs of cylinders at the corresponding ends of the rams, valves controlling said bypasses, check valves permitting flow through said bypasses in one direction only, and means associated with one or the rams for opening said bypass valves individually and respectively as the ram approaches the limit of its travel in the opposite directions whereby the fluid pressure in one diagonally connected pair of cylinders is automatically bypassed to the cylinders of the other pair.

2. An hydraulic motor comprising a pair of rams and cylinders embracing the opposite ends of each of said rams, of means for connecting said cylinders in pairs whereby pressure may be applied to one of said connected pairs simultaneously with evacuation of the other pair of cylinders, bypasses connecting the cylinders of one pair individually and respectively with the cylinders of the other pair, valves controlling said bypasses, check valves permitting flow through said bypasses in one direction only, and means associated with one of the rams for opening the said bypass valves individually and respectively as the ram approaches the limit of its travel in the opposite directions whereby fluid pressure in the one pair of cylinders is automatically bypassed to the cylinders of the other pair.

3. An hydraulic motor comprising a pair of rams and cylinders embracing the opposite ends of each of said rams, of means for connecting said cylinders in pairs whereby pressure may be applied to one of said connected pairs simultaneously with evacuation of the other pair of cylinders, bypasses connecting the cylinders of one pair individually and respectively with the cylinders of the other pair, valves controlling said bypasses, pressure-operated means for opening said bypass valves, means for connecting said pressure operated means respectively with one cylinder of each of said pairs, 2. pilot valve controlling each of said connections, and means associated with one of the rams for opening said pilot valves individually and respectively as the ram approaches the limit of its travel in the opposite directions whereby the fluid pressure in one of said connected pairs of cylinders is automatically bypassed to the cylinders of the other pair.

4. An hydraulic motor comprising a pair of rams and cylinders embracing the opposite ends of each of said rams, of means for connecting said cylinders in pairs whereby pressure may be applied to one of said connected pairs simultaneously with evacuation of the other pair of cylinders, bypasses connecting the cylinders of one pair individually and respectively with the cylinders of the other pair, valves controlling said bypasses, pressure-operated means for opening said bypass valves, means for connecting said pressure operated means respectively with one cylinder of each of said pairs, a pilot valve con-' trolling each of said connections, means asso- 0 ciated with one of the rams for opening said pilot valves individually and respectively as the ram approaches the limit of its travel in the opposite directions whereby the fluid pressure in one of said connected pairs of cylinders is automatically bypassed to the cylinders of the other pair, and means for automatically re-closing said pilot valves following actuation to the open position when the said ram is operated in the opposite directions.

5. An hydraulic motor comprising a pair of mm, a working cylinder at each end of each of said rams, the cylinders of one ram being connected with the cylinders of the other ram whereby pressure may be applied simultaneously to force the rams in opposite directions, bypasses connecting the cylinders at the corresponding ends of the rains together, a valve for each of said bypasses, and means associated with one of said rams for individually opening said valves at predetermined points in the travel of the ram in opposite directions respectively, said means comprising a pressure-operated device for opening each of said valves, means connecting said devices respectively with the cylinders at opposite ends of one of said rams, a pilot valve controlling each of said connecting means, and means associated with the ram of the other cylinders for actuating said pilot valves.

6. An hydraulic motor comprising, a pair of rams arranged substantially in side by side relation, cylinders embracing the opposite ends of each of said rams, piping connecting the cylinders of one ram with the diagonally opposite cylinders of the other ram, whereby pressure may be simultaneously applied to either of said connected pairs of cylinders while exhausting the other, bypass means between said connected pairs of cylinders, normally closed valves in said by pass means, one of said valves controlling the flow of fluid from the cylinders subjected to pressure to the cylinders connected to exhaust when said rams are actuated in one direction, the other of said valves controlling the flow of fluid from the cylinders subjected to pressure to the cylinders connected to exhaust when said rams are actuated in the reverse direction, means for opening one of said valves when the rams approach 00 their limit of travel in one direction, means for opening the other of said valves when the rams approach their limit of travel in the reverse direction, a pump for supplying fluid pressure to said cylinders, and means for urging said valve to 105 closed position.

I ROBERT C. LAMOND.

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