US2918795A

US2918795A - Electro-hydraulic actuating cylinder

Info

Publication number: US2918795A
Application number: US532672A
Authority: US
Inventors: Melvin W Marien
Original assignee: Ramsey Corp
Current assignee: Ramsey Corp
Priority date: 1955-09-06
Filing date: 1955-09-06
Publication date: 1959-12-29
Anticipated expiration: 1976-12-29

Description

' Filed Sept. 6, 1955 1959 v M. w. MARIEN 2,918,795

ELECTRO-HYDRAULIC ACTUATING CYLINDER 2 Sheets-Sheet 1 24 32 3s 35 as 26 23 1512.1

MELVIN W. MARIEN AT TO N EYS INVENTOR.

M. W. MARIEN ELECTRO-HYDRAULIC ACTUATING CYLINDER 2 She ets-Sheet 2 Filed Sept. 16, 1955 vwww mo wwm mo INVENTOR.

MELVIN W. MARIEN BY 1%,, 7M A#e%- TORNEYS United States Patent ELECTRO-HYDRAULIC ACTUATING CYLINDER Melvin W. Marien, Brentwood, Mo., assignor to Ramsey Corporation, a corporation of Ohio Application September 6, 1955, Serial No. 532,672

2 Claims. (Cl. 6052) This invention relates to an actuating mechanism, and more particularly to a self-powered hydraulic unit or fluid motor, and still more particularly to an electrohydraulic actuating cylinder for use as a window opener, a door opener, in power steering, for aircraft controls and flaps, or wherever a remote or otherwise push-pull action is desired, although other uses and purposes may be apparent to one skilled in the art.

Heretofore, where fluid motors, such as hydraulic cylinders, have been employed for use in providing a remotely controlled push-pull operation, it has been necessary to position the pressurized fluid supplying means (prime mover and pump) at a distance from the hydraulic cylinder. Such an installation required long pressure tubes between the fluid pump and hydraulic cylinder which reduced the overall efliciency of the unit. In the past, to eliminate the long pressure tubes, the hydraulic actuating cylinder has, in many cases, been remotely positioned from the job and connected thereto by mechanical linkages which also reduce the overall efliciency of operation. Where long pressure tubes and mechanical linkages have been employed in a hydraulic system, it has been found that such arrangements are quite cumbersome and require a large amount of protected space. Moreover, failure in operation of a hydraulic cylinder or in the desired push-pull operation is extremely hazardous due to the possibility of leakage along the long pressure tubes or breakdown along a mechanical linkage.

In accordance with the invention, a complete hydraulic system is provided in a single package. A common housing encloses a cylinder and piston, a fluid reservoir, a fluid pump communicating with both sides of the piston, and an electric motor. Suitable check and relief valve arrangements are provided to prevent any undue pressure built up at each end of the cylinder and to compensate for the reduced volume at the end of the cylinder connected to the piston rod.

In the preferred embodiment, the pump and electricmotor are carried by the piston, While in another embodiment the pump and electric motor are stationarily positioned at one end of the cylinder.

It is then an object of this invention to provide a Another feature of this invention resides in the provision of an electro-hydraulic actuating cylinder which eliminates the necessity of providing long pressure tubes between the cylinder and source of pressurized fluid, and

eliminates the necessity of having mechanical linkages thasst- 2,918,795 I Patented Dec. 29, 1959 connecting the actuating piston with the element desired to employ the push-pull movement.

Another object of this invention is to provide an electro-hydraulic actuating cylinder having a common housing enclosing a double-faced piston slidable in a cylinder, a fluid reservoir, and a pump-motor unit carried by the piston, wherein it is only necessary to connect the cylinder to a source of electricity for operation.

A still further object of this invention is to provide an electro-hydraulic actuating cylinder having a common housing enclosing a cylinder and a double-faced piston slidable therein, a fluid reservoir, and a pump-electric motor assembly stationarily positioned at one end of the housing, wherein it is only necessary to connect the cylinder to a source of electric power for operation.

Other objects, features, and advantages of the invention will be apparent from the following detailed disclosures, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts, in which, on the drawings:

Figure 1 is a longitudinal sectional view, with parts in elevation, of a hydraulic cylinder constructed in accordance with the principles of the invention;

Figure 2 is a transverse sectional view, taken substantially along the line IIII in Figure l and looking in the direction of the arrows; and

Figure 3 is a longitudinal sectional view, with parts in elevation, of a hydraulic cylinder illustrating a different form of the invention.

As shown on the drawings:

In the preferred embodiment as seen in Figure 1 and Figure 2, the hydraulic actuator 10 includes a common housing 11 that encloses a piston cylinder 12, a doublefaced piston assembly 13 slidable in the cylinder, and an annular fluid reservoir 14. The piston assembly 13 carries an internal gear pump 15 and an electric motor 16, preferably of the induction type.

The housing 11 includes an outer cylindrical shell 17 concentrically positioned with respect to the cylinder 12. The shell 17 and cylinder 12 are closed at each end and held in properly spaced relationship by a rear end head 18 and a front end head 19 in abutting relationship with an end plate 20. A series of annularly arranged elongated nut and bolt assemblies 21 interconnect the end heads 18 and 19 and the end plate 20. It is noted that an annular shoulder 18a on the end head 18, and an annular shoulder 19a on the end head 19 extend inwardly between the opposite ends of the cylinder 12 and the shell 17. An anchoring lug 1812 projects outwardly from the end head 18 to provide means for attaching the housing 11 to any desired structure.

It is noted that the space between the cylinder 12 and shell 17 defines the annular fluid reservoir 14 which is vented at 14a. Any desirable hydraulic fluid may be employed for use in the instant invention.

The piston 13 is relatively elongated and divides the inside of the cylinder 12 into a rear power or fluid chamber 22 adjacent the rear end head 14 and a front power or fluid chamber 23 adjacent the front end head 19. The piston 13 comprises a cylindrical member 24 diametrally size to be freely slidable Within the cylinder 1.2 closed at one end by a disk-shaped wall 25 that is suitably secured thereto. The wall 25 is provided with an annular notch 25a for receiving a resilient packing cup 26. The packing cup 26 may be of any suitable material, such as rubber, leather, etc., and is held in position by a retainer 27 suitably secured to the wall 25, such as by stud bolts or the like (not shown). The retainer 27 is centrally bored and carries a flat circular wall 27a at one end thereof, and a hollow piston rod 28 at the other end The piston rod 28 extends through a centrally disposed aperture in the front end head 19 and end plate 20, and terminates in a connecting lug 28a. The end head 19 is suitable recessed at the outer end to provide an annular space for a plurality of resilient packing rings 29 for providing a seal around the piston rod 28. A rigid ring 30 overlies the packing rings 29 and is held in place by the abutting end plate 20.

The rear end of the piston 13 is closed and is provided with a dividing wall 31 received within the cylinder member 24 and secured thereto, such as by press fitting. The wall 31 is spaced from the end of the cylinder 24 by a spacing ring 32, the outer face of which is in planar alignment with the peripheral edge of the member 24. A resilient packing cup 33 abuts the end of the cylindrical member 24 and a portion of the spacing ring 32, and is secured thereto by a disk-shaped retainer 34. The packing cup 33 may also be constructed in a similar manner as-the packing cup 26. Stud bolts (not shown) or other suitable fasteners may be employed to secure the re tainer 34 to the spacing ring 32. Hence, the piston 13 is double-faced and is divided between its ends by the wall 31 to define a pumping chamber and a motor chamber, the motor chamber being adjacent the piston rod end of the piston.

The motor 16 is received in the motor chamber and is preferably of the reversible induction type. The motor 16 comprises a stator 35 suitably secured to the inner wall of the cylindrical piston member 24, and a rotor 36. The rotor is carried on a shaft 37 that is bearingly supported by the packing cup retainer 34, the dividing wall 31, and the end wall 25. The stator 35, while more or less diagrammatically illustrated, is of such design, such as having a plurality of windings, as to render the electric motor 16 reversible.

Electric wires leading to the stator extend through the disk-shaped wall 25, the closing plate 27a, and the hollow piston rod 28 to terminals on the attaching lug 28a. It may be noted that the rotor 36 is diametrally sized as to be slightly spaced from the stator 35 thereby providing an annular passageway therebetween as indicated by the numeral 38. Moreover, the rotor 36 is of such width as to be spaced from the dividing wall 31 on one end and the disk-shaped wall 25 at the other end as to provide annular passageways around the shaft 37.

To supply pressurized fluid to the

power chambers

22 and 23, the internal gear pump 15 is provided having an impeller 39 in meshing engagement with a rotary internal gear 40, as more clearly seen in Figure 2. The impeller 39 is suitably secured to the shaft 37 such as by the key 39a. Thus, the rotor 36 of the motor 16 is directly connected to the impeller 39 of the pump 15. The spacing ring 32 functions as the body of the internal gear pump 15, and the impeller 39 is mounted eccentrically with the body and actuates the internal gear 40 rotating .in the body or ring 32.

The pump 15 is provided with a pair of combination inlet-

outlets

41 and 42 which are formed in the abutting side plates, in this case, the dividing wall 31 and the retaining member 34, respectively. Each inlet-outlet is in the form of an arcuate slot and diametrically opposed with respect to the impeller 39. The inlet-outlet 41 communicates with the front power chamber 23 through the passageway 38 defined by the rotor and stator of the motor 16 and a passageway 43 extending through the wall 25 and retaining member 27, while the inlet-outlet 42 communicates with the rear power chamber 22 through a suitable aligned opening in the retaining member 34.

When the electric motor 16 is driving the pump 15 in the direction indicated by the arrows 44 in Figure 2 the fluid flow will be from the power chamber 23 to the power chamber 22, thereby permitting the inlet-outlet 41 to function as an inlet to the pump 15, while the inletoutlet 42 functions as an outlet. Fluid will be drawn through the passageway 43, the passageway 38 between the rotor and stator of the motor 16, through the pump 15 and into the power chamber 22. It is understood that the rotor 36 and the stator 35 of the motor 16 will be so protected with insulation as to prevent these elements from being damaged or effected by the hydraulic fluid flow. In other words, the rotor and stator of the motor 16 will be at all times in full communication with the fluid flow between the

power chambers

22 and 23.

Inasmuch as the volume of the power chamber 23 is much less than the volume of the power chamber 22 due to the piston rod 28 extending through the chamber 23, additional fluid is received from the reservoir 14 by the power chamber 23 through a conduit 45, a check valve 46 which allows unidirectional flow from the reservoir 14, a conduit 47 interconnecting the valve 46 with the end head 19, and a curved passageway 48 in the end head 19 intercommunicating the conduit 47 with the power chamber 23. While the check valve 46 may be of any conventional type, it is merely illustrated diagrammatically in Figure 1. If the fluid pressure in the power chamber 22 exceeds a predetermined amount, an adjustable relief valve 49 will open and allow fluid flow to the reservoir 14. The valve 49 is connected to the reservoir 14 through a tubular section 50 and intercommunicates with the power chamber through a bent piece of tubing 51. With fluid flow into the power chamber 22, the piston 13 will, of course move toward the front end head 19, thereby extending the hydraulic unit 10.

In reversing the direction of the pump 15 and the motor 16, fluid flow will be established from the power chamber 22 to the power chamber 23. In order to compensate for the smaller fluid capacity in the chamber 23, excess fluid will be returned to the reservoir 14 through the passageway 48, the conduit 47, and the conduit 45 through a conduit 52, an adjustable relief valve 53, and a conduit 54 connecting in the conduit 45. During this operation, the inlet-outlet 42 performs as an inlet, while the inlet-outlet 4-1, performs as an outlet in connection with the pump 15. And again the fluid flow will pass between the rotor and stator of the motor 16, and through the passageway 43. In filling the power chamber 23 and emptying the power chamber 22, the piston 13 will, of course, move towards the rear end head 18 thereby retracting the hydraulic unit 10.

It will be understood that the check valve 46 and the relief valves 49 and 53 perform as unidirectional flow valves and may be of any conventional type for the intended purpose. These valves and associated tubing intercommunicating the power chambers with the reservoir are more or less illustrated diagrammatically for clarification purposes, but it is understood that these elements will in all probability be confined within the common housing 11. For example the valves 46 and 53 and their associated conduits may easily be confined within the end head 19.

Now referring to Figure 3, a self-powered hydraulic unit 60, illustrating a different form of the invention, includes generally a housing 61 enclosing a fluid cylinder 62, a piston 63 slidable in the cylinder, a fluid reservoir 64, an internal gear pump 65, and an electric motor 66.

The housing 61 includes a cylindrical shell 67 closed at one end by a rear end head 68, and at the other end by a front end head 69. An end plate 70 abuts against the outside wall of the end head 69 and carries a depending flange 70a for mounting the housing 61. The end heads 68 and 69 are annularly notched at 68a and 69a to receive the opposite ends of the cylindrical shell 67. A plurality of annularly arranged nut and bolt assemblies 71 hold the end heads 68 and 69 and the end plate 70 in tightly abutting relationship.

A disk-shaped dividing wall 72 is intermediately positioned between the ends of the cylindrical shell 67 di viding it into two sections. The wall 72 carries an enlarged integral annular ring section, the outer periphery of which is snugly received by the inner wall of the cylindrical housing member 67. The ring section coacts with the main section of the wall 72'to define a pair of aligned

annular shoulders

72a and 72b.

The shoulder 72a receives one end of the fluid cylinder 72, while the other end of the cylinder is received by a shoulder 69b formed in the front end head 69 thereby concentrically disposing the cylinder 62 with respect to the cylindrical housing member 67. One end of a cylindrical shell 73 is received by the shoulder 72b of the dividing wall 72, while the other end of the shell is received by an annular groove 68b in the end head 68. The shell 73 is axially aligned with respect to the cylinder 62 and together define along with the cylindrical housing member 67 the annular fluid reservoir 64. The reservoir is vented at 64a. Also, the shell 73 serves as an enclosure for the motor-pump unit.

The compartment defined by the cylinder 62, the end head 69 and the dividing wall 72 comprises the cylinder section of the hydraulic unit 60, and is divided into a pair of

power chambers

74 and 75 by the piston 63. The piston 63 includes a center disk member 76 freely received within the cylinder 62 and serving as a spacer for a pair of oppositely facing packing cups 77 and 78. The packing cups, of course, sealingly engage the inner wall of the cylinder 62 and are secured to the spacer 76 by

retainer members

79 and 80, respectively. The spacer 76 and the retainer 80 are centrally apertured, and the retainer 79 is centrally tapped to receive one end of a piston rod 81. The piston rod 81 carries an annular flange 81a which abuts against the retainer 80, and the rod is threaded at the very end to be received in the tapped retainer 79. When the rod 81 is drawn up tight against the retainer 80, the retainers, the spacer and packing cups are held together as a unit.

The piston rod 81 extends through a suitably formed hole in the front end head 69 and terminates in a threaded end 81b for connection to a mechanism desired to have a push-pull movement. The rod receiving hole in the end head 69 is radially enlarged at the outer side to receive a plurality of packing rings 82 to sealingly engage the piston rod. A ring member 83 overlies the packing rings 82 and is held in place by the end plate 70.

Referring now to the motor-pump unit, the motor 66 includes a rotor 84 rotatably mounted on a shaft 85, and a stator 86 suitably secured to the inner wall of the cylindrical shell 73. The shaft 85 is bearingly supported at its opposite ends by the rear end head 68 and the dividing wall 72. The stator 86 is of a conventional type providing reversible rotation of the rotor 84, and may be connected to a suitable electric source by the leads 86a extending through the rear end head 68.

The pump 65 is a conventional internal gear pump and includes a side plate 87 and the dividing wall 72 that functions as a side plate, a body member 88 received within the cylindrical shell 73, an internal gear 89 rotatably received within the body 88, and an impeller 90 eccentrically mounted with respect to the body 88 and for actuating the internal gear 89. The body, internal gear and impeller are received between the end plate 87 and the dividing wall 72. The impeller 90 is suitably secured to the shaft 85 by a key member 85a. It is to be understood that the pump 65 is substantially identical with the pump 15 of the embodiment in Figure 1 and Figure 2. The pump is provided with a pair of combination inletoutlets 91 and 92 which are in the form of arcuate openings such as the inlet-outlet 41 shown in Figure 2.

In operation, the hydraulic unit 60 will function in a similar manner as the hydraulic unit 10. It may be noted that the pump inlet-outlet 92 is in direct communication with the power chamber 74, while the pump inlet-outlet 91 communicates with the power chamber 75 through a radial gap 93 existing between the rotor and stator of the motor 66, a passageway 94 in the end head 68, a tubular member 95 supported at each end by the opposite'end heads and intermediately by the enlarged ring section of the dividing wall 72, a passageway 96 in the end head 69, and an annular port 96a opening into the power chamber 75. It is noted that the rotor 84 and stator 86 of the motor 66 are spaced at each end from the end head 68 and the end plate 87 of the pump 65 to provide annular fluid passageways. It is to be understood that the rotor and stator are similarly insulated as the rotor and

stator

36 and 35 of the electric motor 16 in the embodiment shown in Figure 1 as to preclude damage or injury thereby due to the fluid flow therearound. At all times the rotor and stator are in full communication with the fluid flow from the pump 65.

When it is desired to shorten the hydraulic unit 60 or retract the piston rod 81, the motor and pump are rotated in the direction to pump the fluid from the power chamber 74 and into the power chamber 75. During this operation, the inlet-outlet 92 will function as an inlet to the pump 65, while the inlet-outlet 91 will function as an outlet. Pressurized fluid will flow through the pump 65, the gap 93 between the rotor and stator of the motor 66, the passageway 94, the tubular member 95, the passageway 96, and the port 96a. Since the volume of the pressure chamber 75 when the piston 63 is fully retracted is less than the volume of the power chamber 74 when the piston rod 81 is fully extended, excess fluid will be returned to the reservoir 64 through a passageway 97 in the end head 68 into a duct 98a of a valve housing 98, through an adjustable pressure relief valve or unidirectional valve 98b into a return duct 98c, andthrough a return passageway 99 in the end head 68.

In order to extend the hydraulic unit 60 and protract the piston rod 81, the direction of the motor and pump is reversed to draw the fluid from the power chamber 75 and pump it into the power chamber 74, wherein the pressurized fluid will exert a pressure against the end of the piston 63 to move the piston towards the end head 69. During this pump operation, the inlet-outlet 91 functions as in inlet to the pump 65, while the inlet-outlet 92 functions as an outlet. The fluid will then flow from the power chamber 75 into the power chamber 74, and inasmuch as insuflicient fluid in contained in the power chamber 75 to fill the power chamber 74, additional fluid is taken from reservoir 64. This additional fluid passes through the passageway 99 in the end head 68, the duct 98c in the valve housing 98, a unidirectional or check valve 98d, the duct 98a, the passageway 97 in the end head 68, and through the rotor-stator gap 93 to the inlet 91 of the pump 65.

In view of the foregoing, it is seen that an electrohydraulic actuating cylinder is provided which is decidedly compact in size, is operable in any installation upon connection to a source of electrical energy, and is highly eflicient due to'the elimination of long pressure tubes and linkage assemblies.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

I claim as my invention:

1. A self-powered hydraulic unit comprising a casing having a pair of concentric cylindrical members and an end head at each end thereof, a fluid reservoir defined between the concentric members, a double-faced piston slidable within the inner cylindrical member and having a piston rod extending through one of the end heads, a pump and electric motor assembly carried by the piston, said pump having a first inlet-outlet leading to one side of the piston, a second inlet-outlet leading to the other side of the piston, a separate line intercommunicating each side of the piston with the reservoir, an unidirectional valve in each line permitting fluid flow towards the reservoir, a bypass line around said valve serving the piston rod side of the piston, and a second unidirectional valve in said bypass line preventing the fluid flow therethrough towards the reservoir.

2. A self-powered hydraulic unit comprising a casing having a pair of concentric cylindrical members and an end head at each end thereof, a reservoir defined between the concentric members, a double-faced piston slidable within the inner cylindrical member and having a piston rod extending through one of the end heads, a pump and electric motor assembly carried by the piston, said pump having a first inlet outlet leading to one side of the piston, 21 second inlet-outlet leading to the other side of the piston, a separate line intercommunicating each side of the piston with the reservoir, means in each line preventing the return flow of fluid to the respective piston sides, a bypass line around the means serving the piston rod side of the piston, and means in said bypass line preventing the fluid flow therethrough towards the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 1,993,612 Lurn Mar. 5, 1935 2,035,813 Johnson Mar. 31, 1936 2,170,702 Wardwell Aug. 22, 1939 2,308,731 White Jan. 19, 1943 2,449,482 Hufierd Sept. 14, 1948 2,580,262 Worst Dec. 25, 1951 2,599,308 Worst et al. June 3, 1952 2,646,504 Gosline July 21, 1953 2,676,571 Parsons Apr. 27, 1954 2,679,727 McLeod June 1, 1954 2,680,952 Hurkamp et a1. June 15, 1954