US2640429A - Hydraulic power unit - Google Patents

Description

June 2, 1953 s. B. MCLEOD HYDRAULIC POWER UNIT 2 Sheets-Sheet l Filed March 21, 1949 FIGJ.

uvwizvrox. STEWART B. McLEOD 7 w. Mk 8 7 4 \T 0 35 Q b 4 w a 5 a 3 u s F ATTO RN EYS June 2, 1953 Y v s. B. MOLEODI 2,640,429

HYDRAULIC POWER UNIT Filed March 21, 1 949 2 Sheets-Sheet 2 INVENTOR. STEWART B. McLEOD- ATT RNEYS Patented June 2, 1953 HYDRAULIC POWER, UNIT StewartB; McLeod; Dearborn, Mich-., assignor to Detroit. Harvester. Company, Detroit, Mich a corporation of. Michigan Application March 21, 1949, SerialNo. 82,529

2- Claims.

The present invention relates to: a hydraulic power unit and more particularly to a combined pump; motor, reservoirand control valves-therefor.

Th present invention. is capable of general application but may be used in the type of systern disclosed in my prior Patent 2,388,755, granted November 13, 1945;

This application is a continuation in part of my co-pending application, Serial No. 776,635, filed September 29,v 1947, now Patent No. 2,588,644.

In accordance with the present invention, a hydraulic system including'a reversible pump is provided with a by-passand reservoir connec tion unit which serves to seal the pressure side of the pump and open the suction side of the pump to the reservoir to compensate for unequal volumes of flow due to piston rod displacement when the cylindersare used. In one embodiment of the present invention the mechanism is further constructed to afford pressure relief so as to prevent development of excessive pressuresat the pressure side of the pump. Inasmuch as in the presentconstruction the fluid flow is not through th unit to the cylinders or fluid motors, th unit can be made without regard to flow areas through the valve and consequently may be relatively small and inexpensive.

It is an object of the present invention to provide an improved hydraulic power unit characterized by its efficiency, extreme simplicity, the compactness of its arrangement andthe economy with which it may be produced.

More specifically, it is an object of the present invention to combine a pump, motor, reservoir and control valves for supply fluid in a novel arrangement whereby a hydraulic system in which said unit is connected remains always fully charged with fluid.

It is a further object of the present invention toprovide a reversible-pump and reservoir unit in which the reservoir is connected at all times during operation of th pump to the suction side thereof.

It is a further object of the present invention to provide a by-pass connection for a reversible pump which remains open when the pump is idle to provide for manual, operation of normally fluid operated mechanism but which is closed by operation of the pump in either direction.

It is a further object of the present invention to provide a by-pass between the pressure and suction sides of a pump adapted to remain open when the pump is idle, to close during normal pump; operation, and to reopen in the event of excessive pressure at the pressure side of the pump.

It is a feature of the present invention. to. provide a hydraulic power unit comprising a; block having a recess therein for the reception of a rotary pump, a motor supported from the block in driving relation with the pump, passages for circulating fluid communicating at oneside of the recess with opposit sides of the pump, a fluid supply reservoir carried by the block having passages communicating at the opposite side of the recess with opposite sides of said pump, and valves for controlling the. flow of supply fluid between the reservoir and" pump.

Other objects and features of the invention will become apparent as the description proceeds; especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is an elevation, partly'in section, of my improved unit;

Figure 2 is a section on the line 2-2 of; Figure 1;

Figure 3' is a section-on the line 33 of, Figure 2;

Figure-4 is a perspective view of the valve enga-gingelement employed in my improved construction;

Figure 5 is'a section on the line- 5-5 of'Figure 1;

Figure 6 is a fragmentary section on the line 6-6, Figure 5;

Figure '7 is a vertical elevation, partly in; section, of a somewhat different embodiment of'the present invention;

Figure 8, is a section on the line B--8' of Figure Figure 9 is. an enlarged fragmentary section on the line 9-9 of, Figure8.

Thepresent construction comprises a block 0 carried at the top of a motor housing 30: and. supporting at its upper surface a fluid supply be appreciated that the device illustrated is for 3 use in supplying fluid to a hydraulic system and that the system will include conduits having threaded connectors cooperating with the connecting portions I5 and I5. Passages I3 and M serve as inlet and outlet connections to the pump, depending upon the direction of rotation thereof. In other words, th pump is reversible and in one instance fluid will be drawn in through the passage I3 and discharged through the passage I4, whereas when the pump is rotated in the opposite direction, the direction of flow of the fluid is reversed.

Th block I0 is provided with an opening I! the-rethrough which is coaxial with the cylindrical recess II and which receives the drive shaft I8 of an electric motor indicated at I9. The lower end of the opening I? is enlarged to receive a suitable seal and bearing for the shaft I8.

The motor I9 is carried'within the housing which is assembled to the block III by means of long attaching screws 32 threaded into tapped recesses in the block I!) as indicated at 33. A conductor for supplying power to the motor I9 is illustrated at 34.

Located on the upper surface of the block I0 is the reservoir 40. As illustrated, the reservoir may be in the form of a sheet metal cup having a removable closure 4L The bottom 42 of the reservoir 40 is provided with a circular opening 43 surrounding the rotor IZa, and a sealing gasket 44 is provided between the bottom 42 and the upper surface of block I0.

Located within the reservoir 40 is a valve which serves to provide and control fluid supply passages between the reservoir and the pump. A first passage 5| communicates with a short, relatively small transverse passage '53 formed in the central portion of a boss 54. At its outer ends the passage 53 communicates with enlarged end passages or openings and 56. Intermediate the passage 53 and the two enlarged end openings 55 and 56 are conical valve seat portions 51 and 58, respectively. Located within the enlarged opens 55 and '56 are ball valves 59 and 60, respectively. The outer ends of the openings 55 and 56 are closed by threaded plugs BI and 62, respectively, and intermediate the plugs BI and 62 and the ball valves 59 and are balancing springs I53 and 64, respectively. Extending laterally from the enlarged openings 55 and 56 are ports and 65 which communicate with the side of the gear pump opposite to ports or passages I3 and I 4.

Intermediate the ball valves 59 and 60 is a slidable element 81, shown in detail in Figure 4. The element 61 may conveniently be formed of metal of triangular cross section and preferably has rounded corners, as indicated at 69. The element 6'! is slidably received in the passage 53 but byvirtue of its triangular cross section it permits flow of fluid through said passage 53.

The element 61 is of such length that when the ball valves 59 and 6B are symmetrically located with respect to their seats 51 and 58,

respectively, both valves are in partially open position. On the other hand, it will be readily apparent that when one of the ball valves 59 or 60 closes by virtue of pressure existing in the passage with which it communicates, the other of the ball valves is mechanically moved to full open position.

Springs 63 and 64 areof substantially equal strength so that in the absence of pressure in 4 the device the ball valves stand in the position shown in Figure 1.

The assembly of the parts includes the use of assembly bolts 12 (Figure 2) which extend through the valve body 50 into suitably tapped openings formed in the upper surface of the block ID.

The cover or closure 4| for the reservoir 40 is illustrated as secured in place thereon by means of a tie bolt III threaded at its lower end into a suitably tapped recess 10a in the upper surface of the valve body 50 and provided at its upper end with a nut II.

Th under surface of the valve body 50 rests directly on the upper surface of the pump comprising the gear members I2a and I2b and thus constitutes the upper closure for the pump chamber, the lower portion of which is constituted by the cylindrical recess II formed in the upper surface of the block I D.

The valve body 50 is provided with a transverse passage I3 which communicates with an opening 14 provided in the gear member I2?) and which permits flow of oil therethrough to relieve prese sures which might otherwise build up. The gear I2b is provided with a keyway I5 which receives a driving ball or key I6 seated in a recess at the end of the drive shaft I8.-

An oil slinger I8 is carried by the shaft I8 below the bearing structure 20 and any oil which passes downwardly of the shaft below the bearing encounters the oil slinger and is thrown thereby in radial direction. The attaching bolts 32 which connect the motor to the block I0 are provided with oil resistant rubber sleeves I9 which serve to seal passages through which the bolts 32 extend.

The mounting means for the assembly comprises a ring III) to which is suitably secured a bracket II2 having ears H3 provided with openings I M which receive rubber mounting bushings II5. In order to prevent rotation of the motor, pump, valve and reservoir assembly relative to the mounting ring I I8, a recess H6 is provided on the upper surface of the motor housing and a portion of the ring H0 is lanced inwardly to form a finger IIB which seats in the recess H6 and thus serves as a positive means for preventing relative rotation between the ring I In and the remainder of the assembly.

If desired, a similar finger may be provided at the upper edge of the ring I I0 and may cooperate with a correspondingly formed recess provided at the under side of the block I 0. This will serve the additional function of positively preventing even slight relative rotation between the motor (and hence the gear pump members I 2a and I212) and the block I0 and associated structure. Moreover, since the fastening elements 32 are adapted to draw the motor assembly toward the block III,-

they will insure positive clamping of the ring between these elements and will contribute to the rigidity of the structure as well as the proper alignment of the motor shaft in the block III.-v

In addition to serving as means for mounting the unit, the ring I I 0 serves as a closure member for the space between the top of the motor and the under side of the block I0. The top of the motor has a circular boss I 20 recessed at diametrically opposite-points I 2| to receive screws 32 and sleeves 79. Outwardly from the boss I29;

there is provided an annular seat I22 which receives the lower edge of the ring I II]. A plurality; of recesses H9 are provided in the lower edge of v the ring and cooperate with the upper-surface.

of the motor assembly to provide passages which" permit the escape of oil or hydraulic fluid which might otherwise accumulate within the space.

In order to prevent leakage of fluid from the reservoir 40, which might otherwise occur due to motion of the vehicle or inclination of the vehicle, the cover 4!- is provided with an annular sealing ring of inverted U-shape cross section indicated at H5 in Figure l. Thecover 41 has a correspondingly shaped downwardly opening groove H6 cooperating with the sealing ring H5 and beneath the groove N6 the cover 41 has a downwardly and outwardly flaring flange '8. This construction provides a fluid tight seal at the juncture between the cov- 61' 4| and the reservoir 40. 1

In use the cover M is clamped downwardly against the top of the reservoir 40 by means of the nut H threaded to the upper end of the bolt ID. A seal is also provided where. the bolt 10 passes through an opening I in the cover 41. This seal comprises a suitable resilient gasket I22 which may be formed of an oil resistant rubber or the like and which is received in a downwardly flaring cup I2 1. The gasket I22 is in its uncompressed condition somewhat larger than the cup I24. Accordingly, as the nut II is tightened down and the material of the gasket I22 is compressed, it is forced by the cup I24 to expand inwardly and thus to makea fiuid tight seal with the upper surface of the cover 41: and with the upper portion of the bolt Iii. By this construction the reservoir is, rendered fluid tight and the possibility of fluid. spilling or leaking therefrom in use is completely avoided. The sealed construction of the reservoir is rendered possible due to the fact that the entire system in which the power unit is included is a closed system.

The operation of my improved device is believed to be readily apparent, especially when taken in consideration with the full discussion of my prior construction contained in Patent 2,388,755 and my co-pendi'ng application Serial No. 776,635, now Patent No. 2,588,644,. of which the present application is a continuation in part However, for completeness, it may be noted that upon the establishment of pressure by operation of the pump in the circulating fluid passage I4, pressure will simultaneously be established within the enlarged opening 56 and will close the valve it. At this time suction is established in the passage I3 at the opposite side of the block I0 and also in the opening 55. At thisv time, since the ball. valve 60 is forced. on its seat by pressure, the ball valve 59 is in fully open position, thus establishing communication between the interior of reservoir and the suction side of the pump. As a result of this, and in the event that the demand for fluid in the pressure side of the circulating system is more than can be supplied from the suction side thereof, the difierence in fluid required is made up by withdrawing fluid from the reservoir, as will be readily apparent.

Another valuable function of the balanced arrangement of ball valves is serving as a bypass around the pump. Thus where the unit is employed as a power unit for raising and lowering a convertible top, or other use, the balanced valves provide for a limited by-pass flow of fluid around the pump, and permits manual operation of the operated device. In this case flow of fluid is in one direction or the other through the following sequence of passages:

passage I4, the pump, passages 56-553., 65, theother side of pump, and passage 1.3. Slow man ual operation is permitted, whereas rapid op eration with corres onding rapid flow of fluid through the valved'passages will close one the other of the ball valves, depending on the direction of flow.

Referring now to Figures 7 to 9, there is the hydraulic power unit comprises a motor housing 80, a block 8I- serving as the support for a pump 82 including pump gears I03 and H14, a reservoir 8-3 and a by-pass and reservoir connection unit indicated generally at 84. With the exception of the by-pass and reservoir connection unit 85, the construction of this embodiment may be identical with that illustrated in Figure 1 and will therefore not be described in detail.

However, the by-pass and reservoir connection unit 34 provides the additional function of affording pressure relief in the event of attainment of excessive pressures at the discharge side of the pump 82.

The unit 84 is provided at its ends with enlarged chambers 35 and 86 closed by threaded plugs 87 and 88, respectively. Intermediate the chambers and 85 is a passage 89 of reduced diameter forming at its opposite ends valve seats 90- and 9|. A reservoir passage 92 ex.- tends transversely from the unit 8 into the interior of the reservoir 83 and communicates with the reduced passage 89' intermediate the valve seats 90 and 91. Valve elements Stand 94 are provided adjacent the valve seats 9'0 and ill, each or these valves being provided With'a central port Q5, as'best illustrated in Figure '7. The valves 93 and 9d are of non-circular shape and are illustrated in Figure 9 as being hexagonal so as to provide for flow of fluid through the reduced passage either from end to end or from one end to and through the transverse reservoirpassage 92. The ends of the pin 96 are provided with reduced extending portions 91- which are herein illustrated as conical and being of a diameter at their base substantially equal to the diameter of the port 535 formed in the valves. Intermediate the projecting end portions 91', the pin 95 is of somewhat larger diameter than the ports 95 formed in the valves so that when said valves are retained against the enlarged in-- termediate portion of the pin 96 as by spring pressure, the ports 95 are closed.

Balancing spring means are provided and take the form of compression springs 98 engaging the ported valves 93 and 94 at one end and seated at the other end against the plugs 81 and 88, these plugs being provided with centering projections 99 to retain the springs in centered relationship.

Means are provided for connecting chambers 85 and 86 to opposite sides of the pump 82 and these means take the form of passages NH and I02 extending transversely from the chambers 85 and 86 respectively, and communicating with the internal and external gear members of the pump 82.

The operation of this embodiment of the invention is similar to that of the embodiment i1- lustrated in Figure 1. When the pump is idle the springs 98 retain the pin 96 in centered position' and the valves 93 and 94 are bothre tained away from their corresponding valve seats 90 and 9|. At this time a by-pass is open between opposite sides of the pump comprising the passage ll, chamber 85, reduced passage 89, chamber 86 and passage I02. By virtue of-this arrangement a by-pass flow of fluid is permitted when the pump is idle. Therefore, the mechanism to which the pump is connected may be operated manually.

If now the pump is started in either direction pressure will build up at the pressure side thereof which communicates with the chamber 85 or 86 and this pressure will force the valve 93 or 94 onto its corresponding valve seat, thus closing the by-pass passage. However, closure of either valve 93 or 94 results in further opening of the other valve, thereby maintaining open the passage connecting the suction side of the pump with the interior of the reservoir to permit flow of fluid to or from the reservoir to compensate for unequal flow of fluid to and from the hydraulic motor.

If an excessive pressure is built up in either the chamber 85 or 86 as a result, for example, of interference with the normal operation of a device actuated by the hydraulic motor, the bypass connection between opposite sides of the motor is again opened. This is accomplished by virtue of the pressure acting against one end of the pin 96 through the port 95 in the chamber subjected to the high pressure. When this pressure exerts a force sufiicient to overcome compression of the spring opposing movement of the pin 96 away from the valve subjected to the excessive pressure, the pin 96 moves bodily away from said valve and thereby opens the port 95 in the valve. Accordingly, by selecting the strength of the balancing springs 98, the maximum pressure which the pump 82 will deliver may be determined.

It is emphasized that the present construction represents a substantial improvement over my prior construction, particularly as to compactness, simplicity of mounting, efficiency of operation and the economy with which the construction may be produced.

The drawings and the foregoing specification constitute a description of the improved hydraulic power unit in such full, clear, concise and exact terms as to-enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In a hydraulic power unit, a pump housing block having a circular pump recess in its uptom wall having a circular opening therein inregistration with said circular recess and forming an upward extension of said recess, the upper surface of the bottom wall of said reservoir being coplanar with the upper surface of said pump gears, a valve body in said reservoir having a fiat under-surface resting upon the bottomwall of said reservoir surrounding the opening.

therein, the under-surface of said valve body constituting a closure for the upper end of the pump recess, fluid passages in said valve body terminating in ports at the under-surface of said body communicating with said pump recess,

valves in said body controlling the flow of fluid to and from said reservoir, and fastening means assembling said piunp housing block, reservoir, and valve body comprising fastening elements extending through said valve body and the bottom wall of said reservoir laterally outwardly from said pump recess into said pump housing block.

2. Structure as defined in claim 1 which comprises a removable top cover for said reservoir,-

and means for securing said cover in place on said reservoir comprising a rod carried by said valve body and extending upwardly therefrom through said reservoir, and means on said rod engaging said cover.

STEWART B. MCLEOD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 326,345 Taylor Sept. 15, 1885 1,185,639 Dunlap June 6, 1916 1,711,752 Seipt May 7, 1929 1,869,835 Alexander et a1 Aug. 2, 1932 2,023,039 Wells et al Dec. 3, 1935 2,062,045 Van Deventer Nov. 24, 1936 2,067,348 Schaumann, Jr Jan. 12, 1937 2,107,630 Erbach Feb. 8, 1938 2,135,881 Wentworth Nov. 8, 1938 2,222,203 Manseau Nov. 19, 1940' 2,272,926 Squiller Feb. 10, 1942 2,312,686 Campbell Mar. 2, 1943 2,451,799 Brown Oct. 19, 1948 Curtis et al Feb. 6, 1951

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