US2641106A - Electrohydraulic system having a safety shutoff valve for its accumulator - Google Patents

Description

June 9, 1953 A. F. JELINEK 2,641,106

ELECTROHYDRAULIC SYSTEM HAVING A SAFETY SHUTOFF VALVE FOR ITS ACCUMULATOR Filed Jan. 5, 1952 ENT0R. Aim-P50 f. (/54 lA/EK.

ATTORNEx Patented June 9, 1953 1 ELECTROHYDRAULIC SYSTEM HAVING A SAFETY SHUTOFF VALVE FOR ITS ACCU- MULATOR Alfred F. Jelinek, Cincinnati, Ohio, assignor to The Cleveland Automatic Machine Company, Cincinnati, Ohio, a, corporation of Ohio Application January 3, 1952, Serial No. 264,815

5 Claims.

Thi invention pertains to improvements in hydraulic systems, especially systems for use in conjunction with high pressure hydraulic diecasting machines.

In machines of the above mentioned type there is provided a hydraulic system in which is in corporated a large accumulator bottle charged with nitrogen gas compressed under high prespulls are operated from this same accumulator system if desired.

In diecasting machines of the aforementioned type there is required a furnace for melting the metal to be cast. Further, the hydraulic fluid used in the hydraulic system associated with the machine is very light and also very inflammable especially when coming in contact with an open flame or with the molten metal being provided from the furnace. In certain cases as when diecasting zinc, the furnace is mounted directly on the diecasting machines. In other cases where aluminum or similar alloys are used, the furnace is mounted very close to the machine to allow the operator to ladle the metal into the shot sleeve. I'he close positioning of these furnaces on the machine and to the hydraulic system presents a definite fire hazard due to the highly inflammable hydraulic oil. In cases Where leaks would develop and when these leaks occur and direct oil into the open flame of the furnace or into the molten metal, a fire may result. It is therefore important to minimize the amount of oil fed to such a fire should a leak develop in the hydraulic system.

In most diecasting machine installations a master switch is located at a remote point which allows theoperator to escape from the immediate vicinity of the machine and reach the switch for stopping the hydraulic pump motors of all of the diecasting machines in a particular department. However, de-energizing the pump motors is not the complete answer to minimizing the amount of oil fed to the fire. If the leak or break occurs in the accumulator system, that is, at any point from the accumulator bottle to the shot or core cylinders, shutting down the main line switch and the hydraulic pump will not stop the accumulator from completely emptying it entire contents under the influence of the expanding nitrogen gas. Ordinarily hand operated shutoff valves are provided at the discharge end of the accumulator bottle. However, such hand operated valves are not automatic in operation should it be necessary for the operator to immediately remove himself from the presence of the machine, nor do they act quickly enough that the operator may close them off before serious fire results.

It is therefore the object of this invention to provide an automatic control valve system in the hydraulic circuit of a diecasting machine for automatically shutting off discharge from the accumulator bottle whenever the main stop switch or the main line switch or power supply is otherwise disconnected from the diecasting machine.

Still another object of this invention is to provide a rapidly acting solenoid control valve system which automatically positively closes off discharge from the accumulator bottle in the hydraulic system whenever power supply is disconnected from the regular hydraulic pump of the machine.

It is still another object of this invention to provide an improved hydraulic control apparatus for a hydraulic diecasting machine circuit which substantially instantly and automatically cuts ofi discharge from the accumulator bottle of the hydraulic circuit whenever power supply to the machine is disconnected.

Further features and advantages of this invention Will appear from a detailed description of the drawing in which the drawing illustrates a preferred form of hydraulic circuit incorporating the improved features of this invention.

Referring to the drawing, there is illustrated diagrammatically the basic electric and hydraulic control apparatus used in connection with a modern high pressure hydraulic diecasting machine .iicorporating the features of this invention. All

of the various supplementary holding electric contacts and other features of well known character have been eliminated from the diagram so as to direct its subject matter to the essential basic features to show the environment in which the refinements of applicants invention have been applied.

In a high pressure hydraulic diecasting machine there is provided the usual hydraulic pump l which is driven by the hydraulic pump motor 2 connected thru leads 3 and the contacts 4 to the power supply lines 5 which in turn are connected to the main disconnect line switch fixed to the power supply leads Ll, L2 and L3. A control circuit is provided utilizing a start push button 1 and a stop push button 8, the latter of which is normally closed at all times whereas the start push button I is preferably of momentary contact type. When the start button 1 is pressed with the master switch 6 closed, power is supplied from lead L2 thru lead 9, the stop push button 3, lead 10, the start button 1 and the lead I l to energize the relay coil l2 which in turn is connected to a lead I3 thru a line L3 so as to close contacts 4 and apply power to the hydraulic pump motor 2, suitable holding contacts, not shown, being provided to maintain power supply to the motor 2 after the start button I has been released.

The fluid pressure pump I driven from the motor 2 receives a supply of fluid thru the suction line I 4 from the fluid reservoir I5 and transmits this fluid under high pressure into the high pressure line It which is connected thru a line I! to the shot cylinder control valve I8. A connection is also made from the line I6 thru the line I9, the check valve 26, the line 2I and a pressure regulating valve 22 and a line 23 to the shot cylinder control valve I8. The valve I8 is connected thru suitable lines 24 and 25 to the shot cylinder 26 or to other additional cylinders as may be required for manipulating the core pulls of the machine. The line H is also connected thru a line 21 to supply pressure to the pilot control solenoid operated valve 28 for the control valve I8. Pilot control lines 29 and 36 are respectively connected to the pilot operating cylinder 3| and 32 for shifting the valve I8 upon manipulation of the valve 26 in a well known manner. A suitable drain line 33 is connected to a line 34 to return discharge fluid from the valve 216 to the reservoir I5.

The pilot control valve 28 is operated by the solenoid coils 35 and 36 which are connected at one end thru a lead 3! to the lead II so as to bring them into the circuit whenever the start button I is pressed. The other ends of the coils 35 and 36 are connected thru respective control switches or push buttons 38 and 39 thru the leads 46 and M which in turn are connected thru a lead 42 to the power supply line L3.

There is also provided an accumulator system in conjunction with the above described hydraulic circuit comprising an accumulator bottle 43 in the upper portion 44 of which there is supplied nitrogen gas thru the line 45, stop cock 46, line 41 and stop cock 43 at asuitable pressure, usually approximately 500 pounds as indicated by a suitable gauge 49. Having thus applied gas under pressure in the bottle 43 the stop cook 46 is closed on and the stop cock 48 may be left open to indicate the reading on the gauge 49 or closed during the operation of the machine as desired. The lower end of the accumulator bottle is connected thru a line 50 a manually operated stop cock SI and a line 52 thru the automatic shut off valve 53 to the pressure supply line 2! connected as described to the pump I. The valve 53 is provided with a plunger 54 which is normally urged to a downward position against the stop surface 55 of the pressure chamber 56 by aspring 51 so that its large cylindrical diameter portion 58 of the plunger 54 cuts off the inlet port 59 to which is connected the line 52 from the accumulator bottle so as to prevent any escape of hydraulic liquid 60 from the accumulator bottle 43 under the influence of the gas pressure in the upper portion 44 of the bottle 43.

A control valve comprising a valve body liI in which is slidably mounted a plunger 52 which is actuated by a solenoid coil 63 having one of its leads connected thru a lead 64 to the'lead I I and having its other side connected thru a lead 65 to the line L3 so that the coil is energized whenever the start button I is pressed and deenergized when the circuit is opened by actuation of the stop button 8 or the main line control switch 6 or otherwise disconnecting the power supply from the lines LI, L2 and L3. The valve is shown in the drawing in position when solenoid 63 is energized. Fluid pressure from the pump I is connected thru a suitable regulating valve 66 connected to the line l6 and discharged thru a line 61 to the valve 5|. A discharge drain line 68 is also connected to the valve GI and in turn connected t the discharge drain line 34. A pressure and discharge supply line 69 interconnects the valve BI with the pressure chamber 56 of the valve 53.

The operation of the above described circuit is substantially as follows:

With the main line switch 6 closed the operator presses the start push button I so as to energize relay coil I2 to close contact 4 to apply electrical power to the drive motor 2 for the hydraulic pump I, thus starting operation of the pump and the application of pressure in the pressure supply line I6 as described. At the same time that the start button I is pressed relay coil 63 is energized so as to shift the plunger 62 against the bias spring III of the valve EI so as to interconnect fluid pressure from the pump I thru the line 61 and the line 69 to the pressure chamber 56 of the valve 53 so as to shift the plunger 54 upwardly as shown in the diagram, to interconnect line 52 with line 2I so as to connect the accumulator bottle 43 into the hydraulic circuit.

At the same time that the start button I is pressed, thru suitable holding coils, not shown, energy is also now applied to the solenoid coils 35 and 36 so that when the push button switch 38 is actuated the valve 28 will be operated so as to apply fluid pressure to the pilot cylinder 32 of the valve I8 and release pressure from the pilot control cylinder 3| of said valve. In this position fluid pressure from the pump to the line I6, check valve 26, line 2|, regulating valve 22 and line 23 is connected thru line 25 into the forward pressure chamber II of the cylinder 26 so as to cause this cylinder to move its piston I2, piston rod I3 and connected die apparatus, not shown, toward squeezed position. At the same time gas pressure in the chamber 44 of the accumulator bottle 43 forces out the hydraulic fluid 60 at a rapid positive rate thru the valve 5I which is in open position, and the valve 53 to the line 2I to supplement the pump pressure I for a very rapid movement of the piston I2 to squeezed up position. As soon as the piston reaches squeezed up position the fluid pressure pump then takes over to provide the final high pressure drive for positive positioning of the apparatus.

When the operator presses the control switch button 39 coil 36 of valve 28 is thus energized to reverse the process and now apply fluid pressure from the pump I to the line 24I I to the return pressure chamber I4 of the cylinder 26 to return the cylinder to retracted position. The accumulator bottle 43 has the liquid 66 forced back into it to recharge the pressure in the accumulator by compressing the gas 44 therein from the fluid pressure pump whenever the piston I2 reaches either end of its travel in the cylinder 26 in a well known manner. Thus the accumulator at all times is provided with a potential pressure discharge of liquid 66 so that should a leak develop in any of the circuit beyond the valve 53 a serious fire hazard may develop should this liquid come in contact with the aforementioned heating furnaces necessarily associated with diecasting machines of this type. Should such a leak develop the operator need merely press the stop push button 8 or pull the line switch 6 whereupon coil 63 of the valve BI is instantly tie-energized allowing the spring 10 to move the plunger 62 to the left in the diagram closing off the pressure supply line 61 and connecting the line 69 from the pressure chamber 55 of the valve 53 to the drain line 68. Under these conditions the spring 51 of the valve 53 instantly returns the plunger 54 downwardly so that its cylindrical portion 58 efiectively blocks ofi discharge from the line 52 and from the accumulator bottle without requiring the operator to laboriously and slowly close the manual valve 5| and thus expose himself to potential fire hazards. Thus the potential stored energy in the accumulator bottle is kept confined therein instantly upon disconnecting of the electrical circuit by manipulating the stop push button 8 or opening the main line switch 6, both of which may be done from a remote point away from the machine.

While the apparatus herein disclosed and described constitutes a preferred form of the invention, it is also to be understood that the apparatus is capable of mechanical alteration without departing from the spirit of the\invention and that such mechanical arrangement and commercial adaptation as fall within the scope of the appendent claims are intended to be included herein.

Having thus fully set forth and described this invention what is claimed as new is:

1. In a hydraulic system having a fluid pressure pump, an electric motor for driving said pump, a fluid motor connected to said pump to be actuated thereby, a hydraulic accumulator bottle, means for connecting said accumulator bottle to said pump and fluid motor, control valve in said means, and electrical apparatus for connecting a power supply to said electric drive motor and said control valve whereby the energized electric drive motor and valve causes said pump to operate to supply fluid pressure to said accumulator and to said fluid motor and wherein disconnecting said power supply causes said accumulator to be shut ofl from said pump and said fluid motor independent of the fluid pressure from said pump.

2'. In a hydraulic system having a fluid pressure pump, an electric motor for driving said pump, a fluid motor to be actuated from said pump, an accumulator bottle, means for connecting said accumulator and said pump to said fluid motor, including an automatic cutoff valve between said accumulator bottle and said pump and fluid motor, spring means for normally holding said valve in closed position, and electrically actuated means for holding said valve in open position when said fluid pressure pump electric drive motor is energized.

3. In a hydraulic system having a fluid pressure pump, an electric motor for driving said pump, a fluid motor to be actuated from said pump, an accumulator bottle, means for hydraulically connecting said accumulator and said pump to said fluid motor, including an automatic cutoff valve between said accumulator bottle and said pump and fluid motor, spring means for normally holding said valve in closed position, electrically actuated means for holding said valve in open position when said fluid pressure pump is being driven by said electric motor comprising a control valve interconnected hydraulically between said pump and said cut ofi valve, spring means for normally holding said control valve in closed position to cut oil fluid pressure from said pump from actuating said out ofl valve to open position, electrically operated solenoid means for actuating said control valve when said electric motor for driving said pump is energized to move said control valve to open position to apply fluid pressure from said pump to open said out off valve to thereby hydraulically connect said accumulator bottle with said fluid pressure pump and said fluid motor.

4. In a hydraulic circuit for a diecasting machine including a hydraulic pump, an electric drive motor for said pump, a fluid motor for actuating said diecasting machine apparatus, an accumulator bottle, and means for interconnecting said pump said accumulator bottle and said fluid motor in an operative hydraulic circuit including, an automatic cutoff valve interconnected between said accumulator bottle and said pump and said fluid motor including a fluid pressure actuating means for moving said out off valve to open position, a control valve for applying fluid pressure from said pump to said fluid pressure actuating means for actuating said cutofi valve, electrical apparatus for actuating said control valve to connect said pump to said fluid pressure actuating means, spring means to return said cutofi valve, and switch means for applying or disconnecting electrical power to said drive motor for said pump andsaid electrical apparatus for actuating said control valve so that when said power is disconnected therefrom, said cutoff valve automatically returns by said spring means to disconnect said accumulator bottle from said hydraulic circuit.

5. In a hydraulic control circuit for a diecasting machine having an accumulator bottle, a fluid pressure pump, an electric drive motor for said pump, a fluid motor to be actuated from said pump and bottle, an automatic cutoff valve connected in the discharge line from said accumulator bottle, spring means for normally urging said valve to closed position, a fluid pressure chamber in said valve for actuating said valve to open position to connect said accumulator bottle discharge to said pump and said fluid motor, a control valve hydraulically connected to said cutoff valve including a plunger, spring means for normally urging said plunger to a closed position so that fluid pressure from said pump connected thru said control valve to said pressure chamber in said cutofi valve may be shut off therefrom, a solenoid actuating means for said valve plunger operable when energized to connect fluid pressure from said pump to said pressure chamber in said cutofl" valve, and electrically operated means for simultaneously energizing or deenergizing said electric drive motor connected to said fluid pressure pump and said solenoid actuating means for said control valve.

ALFRED F. JEIJNEK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,298,512 Rockwell Oct. 13, 1942 2,566,381 Svenson Sept. 4, 1951 FOREIGN PATENTS Number Country Date 911,307 France Mar. 11, 1946

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