US2636347A

US2636347A - Electrohydraulic actuating device

Info

Publication number: US2636347A
Application number: US172182A
Authority: US
Inventors: Grebe Otto; Sussebach Walter
Original assignee: ELMEG Elektro Mechanik GmbH
Current assignee: ELMEG Elektro Mechanik GmbH
Priority date: 1949-07-05
Filing date: 1950-07-05
Publication date: 1953-04-28
Anticipated expiration: 1970-04-28

Description

April 28, 1953 o. GREBE ETAL 2,636,347

ELECTROHYDRAULIC ACTUATING DEVICE Filed July 5, 1950 INVENTORS. O GRE E AND VAL-TE use c PY R S 5 8A H Patented Apr. 28, 1953 UNITED STATES PATENT OFFICE ELECTROHYDRAULIC ACTUATING DEVICE Otto Grebe, Olpe, and Walter Sussebach, Gerlingen, near Olpe, Germany, assignors to Elektro-Mechanik G. 111. b. H., Olpe, Germany Application July 5, 1950, Serial No. 172,182 In Germany July 5, 1949 The present invention relates to an electrohydraulic actuating device, and more particularly to such a device comprising an electric motor, a pump coupled with the motor and a piston driven by the oil displaced by the pump.

It is an object of the present invention to render the parts easily insertable into and removable from the tank holding the oil.

It is another object of the present invention to reduce the overall height of the electro-hydraulic actuating device.

It is a further object of the present invention to provide an electro-hydraulic actuating device of the kind described which needs thesmallest possible quantities of material of construction.

It is still another object of the present inven:

tion to provide anelectro-hydraulic actuating device of the kind v described having an entirely closed structure.

It is a still further object of the present invention to provide an electro-hydraulic actuating device which is sturdy and capable of resisting heavy loads.

An embodiment according to the present invention comprises an oil tank having an end plate, an electric motor arranged in the tank, a centrifugal oil pump arranged in the tank coaxially to the motor and being driven by same, a piston arranged for axial displacement in the tank and coaxially to the. motor and the ump and being driven by the oil displaced by the pump, the motor, the pump and the piston being combined to a structural unit with the end plate so that they can be inserted into and removed from the tank as a whole, a stator winding, and a rotor, the stator winding and the rotor both forming part of the motor and being arranged for open contact with the oil in the tank so as to be submerged in oil, whereby the heat generated in the motor is transferred to the oil tank substantially by transfer through the oil.

Preferably a cylinder encloses the piston and is combined to the structural unit with the motor, the pump and the piston. v

In an embodiment according to the present invention the motor is arranged below the pump and the piston and a bearing plate for the motor is arranged above the motor in the tank, the cylinder enclosing the pistonbeing firmly held between the end plate and the bearing plate;

Preferably the pump is arranged on one end of the shaft of the motor.

According to an embodiment of'the present inventionthe rotor issecuredtoathe shaft of the motor so as to permit an axial displacementbetween the rotorandthe shaft.

9 Claims. (CI. 60-52) In an embodiment of the present invention the tank is provided with a lid to which is secured a casing for accommodating the terminals for the electric motor.

According to an embodiment of the present invention the piston is bell-shaped and encloses the p mp- According to an embodiment of the present invention the side wall of the oil tank is provided with means for securing the oil tank to a support.

According to an embodiment of the present invention the piston is provided with a piston rod extending through the hollow shaft of the motor which is arranged in the tank above the centrifugal oil pump and the piston.

Preferably a partition is arranged in the tank and thelower bearing plate of the electric motor and the partition form a casing for the pump.

, According to an embodiment of the present invention means are provided for tightening the stator winding, the bearing plates, the pump casing and the cylinder between the lid and the bottom of the tank. These tightening means include preferably fittings arranged in the bearing plates and the bottom for concentrically holding the stator winding, the pump casing and the cylinder. Preferably the fittings for the cylinder are designed asa plurality of concentric grooves for enabling cylinders having different diameters to be fitted. p

According to an embodiment of the present invention the electric motor is arranged in the lower portionof the tank'and has a substantially vertical shaft having an axial boring having an opening at the lower end thereof communicating with the interior of the tank; the piston is holv lowand the pump is mounted in the hollow piston and a solid shaft isconnected to the pump and engages the-boring of the shaft of the electric motor so as to permit axial displacement of the shafts with respect to each other. Preferabl the solid shaft has part of square cross-section which engagesa boring of the shaft of the electric motor. .The .novel features which are considered as characteristic for the invention are set forth in particular inthe appended claims. The inven- \tionxitself, however both as to its construction and itsmethodof operation, together with addi .tional' objectsand advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanyingdrawing, in which the figure is a;sectional elevationof an embodiment of the present invention.

Referring now to the drawing an oil tank 10 is shownfwhich encloses all important parts of the apparatus. In the lower portion of the tank ii) an electric motor I! is arranged which has a lower bearing plate l2 and an upper bearing plate i3. A centrifugal pump 15 is connected to the shaft 25 of the rotor, the housing of which is formed by a piston l6 arranged for axial displacement in the tank It. A piston rod H is connected to the piston l6 and leads upwards through a gasket H3. The piston rod l'i ends in a preferably square piece 23 provided with an eyelet (not shown) for connection to the device to be actuated (not shown). The tank IQ is provided with a casing 43 in which terminals M are arranged to which the current leads M4 of the stator winding 25 of the motor H are connected.

The operation of this device is as follows:

The tank Hi is filled with oil. If the motor I and the pump [5 are started the oil is sucked from the space above the piston to the space below the same so that the piston it moves and actuates the device (not shown), such as a brake, a press or the like, connected to the piston rod H by means of the square end piece 23. If the motor l'! is stopped the piston 15 and the pump i5 are axially displaced downwards by the force of a spring or a weight (not shown) which are tensio ed or lifted, respectively, during the working stroke.

its will be understood from the drawing, not only the pump l5 and the piston 16 are submerged in oil but also the windings of the motor H In this manner local heatings of the windings 25 which'occur for instance if only one phase of the windings is supplied with current are avoided or balanced and the overloaded winding is protected against burning. If desired the windings 25 of the motor H can be impregnated with an oil-proof lacquer. If the motor H has a cage armature the cage is provided with an oil-proof layer of lacquer ortin.

Preferably the resistance of the rotating parts, particularly of; the rotor of the motor, against the liquid is so chosen that at a stopping of the motor the pump is braked as rapidly as possible thereby reducing the time period which the piston it needs to. return into the initial position thereof. As a further means for reducing this time period the viscosity of the oil is chosen in dependence on the temperature in such a manner that at the stationary operating temperature of i the liquid, for instance 17 C., sufiicient resistance of the liquid is left for braking the rotating parts. Furthermore it is advantageous in many cases to use as a liquid an oil having a high vis-. cosity at low temperatures so that in starting the motor and the pump an increased frictional load is generated which heats the oil rapidly to the stationary temperature thereof.

Preferably the liquid is an oil having a high specific gravity such as chlorinated diphenyl having a specific gravity of approximately 1.5.

The oiltank it! is closed at the lower end thereof and is provided with an end plate or lid 24 at the upper end thereof. The piston I6 moves in a cylinder 38 surrounded by an annular space 31 which is connected by apertures 32 to the space 33 in the upper part of the cylinder 30. The annular space 31 is connected with the suction side of the pump l5 by means of apertures 34. At

' tor ii, the pump 15; the piston l6 and thecyline.

der 39 to the lid 24. As will be seen from the and encloses the pump i5.

drawing the motor is a three-phase motor having three terminals M, and three leads hi4. In the lower part of the tank it] are arranged three fuses 5!, one for each phase of the windings 25. The fuses are connected respectively in series to the stator windings and can be replaced by temperature-responsive switches. The fuses or temperature-responsive switches interrupt the current supply to the windings ii the temperature thereof exceeds a pre-determined limit.

All essential structural parts such as the motor ii, the pump i5, the piston 56 and the cylinder 38 are secured to the lid 24 and connected to the same as a structural unit which can be ini sorted into the oil tank iii and removed from the The piston i6 is bell-shaped It can be designed, if desired, so as to enclose in its initial position the motor H as well. The pump I5 is secured to the upper end of the shaft 26 of the motor II. If a similar arrangement is provided for the rotor of the motor H the lower bearing plate 12 can be dispensed with and thus the axial length of the apparatus may be further reduced.

The cylinder 36 is firmly held between the lid 24 and the upper bearing plate IS, the centering of the cylinder being effected by annular fittings it and id, in the lid 2A and the upper bearing plate i3, respectively. If the lid 24 and the bearing plate i3 are provided with a plurality of annular fittings 43', M having diiierent diameters, cylinders, pistons and pumps having difierent diameters can be inserted so that at equal dimensions of the motor and; the oil tank different actuating forces and times may be accomplished.

If desired the bottom of the oil tank in may be designed as a separate part and the piston pump motor and the cylinder can be connected to the bottom as a structural unit which can be easily inserted and removed.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of electro-hydraulic actuating devices diitering from the types described above.

While we have illustrated and described the invention as embodied in an electro-hydraulic actuating device comprising an electric motor, a pump coupled with the motor, and a piston driven by the oildisplaced by the pump, we do not intend to be limited to the details shown, since same as a whole.

' various modifications and structural changes may be made without departing. in any way. from the spirit of my invention.

Without further analysis, the foregoing will so fully reveal the gist of our invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from thestandpoint of prior art, fairly constitute essential characteristicsof thew generic or specific aspects. of this, inventon and, therefore, such adaptations should and areintended to be comprehended, withinthe meaning and range of; equivalence of the following. claims.

What we claim asnew anddesireto secureby Letters Patent is:

1. An electro-hydraulic actuating device-comprising in combination, an oil tank'having an end. plate; an electric motor arranged insaid tank; a centrifugal oil pump arranged in said tank coaxially .tosaid motor andbeingndlfiyfin by same; a. piston arranged: for axial displacement in said tank. and coaxially. to saidmotor, andsaid pump and being: driven by. the oil. displaced by said pump; said motor, said pump and said piston being combined to a structural 'unit with said end plate so that they can be inserted into and removed from said tank as a whole; a stator winding; and a rotor, said stator winding and said rotor both forming part of said motor and being arranged forfopen contact with the oil in said tank so as to be' submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

with said end plate so that they can be inserted into, and removed from said tank as a whole; a

stator winding; and a rotor, said stator winding H and said rotor both forming part of said motor and being arranged for open contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

3. An electro-hydraulic actuating device comprising in combination, an oil tank having an end plate; an electric motor arranged in said tank; a centrifugal oil pump arranged in said tank coaxially to said motor and being driven by same; a piston arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump, said motor being arranged below said pump and said piston; a bearing plate for said motor arranged above said motor in said tank; a cylinder enclosing said piston and firmly held between said end plate and said bearing plate, said motor, said pump, said cylinder and said piston being combined to a structural unit with said end plate so that they can be inserted into, and removed from said tank as a whole; a stator winding; and a rotor, said stator winding and said rotor both forming part of said motor and being arranged for open contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

4. An electro-hydraulic actuating device comprising in combination, an oil tank having an end plate; an electric motor having a shaft and arranged in said tank; a centrifugal oil pump arranged at one end of said shaft in said tank coaxially to said motor and being driven by same; a piston arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump; said motor, said pump and said piston being combined to a structural unit with said end plate so that they can be inserted into, and removed from said tank as a Whole; a stator winding; and a rotor, said stator winding and said rotor both forming part of said motor and being arranged for open contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

5. An electro-hydraulic actuating device coma piston arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump, said motor being arranged below said pump and said piston; a bearing plate for said motor arranged above said motor in said tank;

[a cylinder enclosing said piston and firmly held between said end plate and said bearing plate, said motor, said pump, said cylinder and said piston being combined to a structural unit with said end plate so that they can'be inserted into,

and removed from said tank as a whole; a stator winding; and a rotor, said stator winding andv "said rotor both forming part of said motorand being arranged foropen contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through. the oil.

An electro-hydraulic actuating device-comprising in combination, an oil tank having a lid; an electric motor arranged in said tank; terminals for said electric motor; a casing secured to said lid for accommodating said terminals; a centrifugal oil pump arranged in said tank coaxially to said motor and being driven by same; a piston arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump; said motor, said pump and said piston being combined to a structural unit with said end plate so that they can be inserted into, and removed from said tank as a whole; a stator winding; and a rotor, said stator winding and said rotor both forming part of said motor and being arranged for open contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

7. An electro-hydraulic actuating device comprising in combination, an oil tank having an end plate; an electric motor arranged in said tank; a centrifugal oil pump arranged in said tank coaxially to said motor and being driven by same; a bell-shaped piston enclosing said pump and arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump; said motor, said pump and said piston being combined to a structural unit with said end plate so that they can be inserted into and removed from said tank as a whole; a stator winding; and a rotor, said stator winding and said rotor both forming part of said motor and being arranged for open contact with the oil in said tank so as to be submerged in oil, whereby the heat generated in said motor is transferred to said oil tank substantially by transfer through the oil.

8. An electro-hydraulic actuating device, comprising in combination, an oil tank having an end plate; an electric motor arranged in the lower portion of said tank; a centrifugal oil pump arranged in said tank coaxially to said motor and being driven by same; a piston arranged for axial displacement in said tank and coaxially to said motor and said pump and being driven by the oil displaced by said pump; said motor, said pump and said piston being com-