IE41854B1 - Hydraulic control unit - Google Patents

Description

The present invention relates to a hydraulic control unit, and more particularly to such a unit which is adapted to control the flow of fluid to a hydraulic motor, which may be used for a variety of different purposes. The invention is, for example, applicable to control unit for controlling the flow of fluid to a hydraulic Steering motor of a steering system of a vehicle.

Examples of hydraulic control units whieh are operated upon the manual steering of a vehicle to direct the flow of fluid to a steering motor associated with the steering mechanism of the vehicle are shown in United States Patent Specification Nos. 2,984,215: 3,443,378: and 3, 613,364.

The units shown in the above-mentioned patent specifications include a valve mechanism which is operated upon turning of the steering wheel of the vehicle to direct the flow of fluid to the steering motor. The valve mechanism is associated with a gerotor gearset such that the fluid flows through the gerotor*· gearset and then into the steering motor. The gerotor gearset meters the flow of fluid to the steering motor as the. steering wheel is turned so that there is a proper follow-up relationship between the turning . of the. steering wheel and the turning of the dirigible wheels of the vehicle for effecting steering of the vehicle. In general, the known designa are relatively expensive to manufacture and are relatively complicated. In addition, the known designs are relatively large in size due. to the- structural '.relationship of the parts thereof.

Typically the valve mechanism which controls the flow of fluid to. the steering motor is a rotary valve i.e., the valve has a valve part directly connected to the steering wheel to rotate upon rotation of the steering wheel. This results in the need for an interconnection between the steering shaft and the rotating valve -2418 5 4 part. The juxtaposition of the various parts has resulted in the need for the steering shaft or a part connected therewith to extend through or into the rotary valve so as to he mechanically interconnected with the rotatable valve part. This has resulted in the necessary requirement that the rotary valve have a diameter which is of sufficient size to allow for the steering shaft to be so positioned. This likewise has resulted in a relatively large package size for the unit, and creates leakage problems.

The above-mentioned disadvantages associated with control units wherein the valve part is directly connected to the steering shaft or part thereto are overcome or minimised in the control units disclosed in Patent Specification Noe. and attention is directed to the claims of the complete Specifications of these applications).

The present invention, which provides a control unit for controlling fluid flow to a fluid motor,said control unit comprising valve means for directing fluid to said fluid motor in response to rotation of an input shaft about an axis, said valve means comprising a fixed valve part and a movable valve part, said fixed and movable valve parts defining passages for directing fluid to said fluid motor upon relative movement of said valve parts, a metering means . for directing a metered flow of fluid to said motor through said valve parts upon rotation of said input shaft and including an externally toothed gear member supported for limited rotational movement and an internally toothed gear member supported for orbital and rotational movement relative to said externally toothed gear member, said internally toothed gear member and the teeth of said gear members defining fluid pockets which expand and contract on relative orbital and rotational movement of the gear members, commutator valve means for controlling -341854 fluid flow to and from the fluid pockets formed by the gear members, a drive sleeve member having a portion drivingly connected with said input shaft for joint rotation therewith about said axis, said drive sleeve member having internal gear teeth, said internally toothed gear member having external gear teeth around the periphery thereof in meshing engagement with said internal gear teeth of said drive sleeve, a mechanical Connection for transmitting torque from said externally toothed gear member to said movable valve part to move same relative to said fixed valve part in response to rotation of said externally toothed gear member, the intermeshing gear teeth of said drive sleeve and said internally toothed gear member and Of said internally toothed gear member and said externally toothed gear member being effective to rotate and orbit said internally toothed gear member and to rotate said externally toothed gear member to transmit torque to said movable valve part upon rotation of said input shaft, is embodied in the unit shown in Figures 18 and 19 of Patent Specification Ho. 4/^2 In order that the present invention may be well understood, some of the control units shown in Patent Specification Jto. ^/#J?2 including the control unit which is an exemplary embodiment of the present invention, will now be described with reference to the accompanying drawings, in which: Pig. 1 is a schematic view illustrating a control unit in a steering system: Fig. 2 is an axial cross sectional view of the control unit shown in Fig. 1.

Fig. 3. is a view illustrating a gerotor gearset of the unit of Fig. l.j Fig. 4 is a cross-sectional view of the unit, of Fig.2 with parts -441854 omitted, taken along the section line 4 - 4 of Fig. 2; Fig. 5 is a cross-sectional view of valve parts of a valve mechanism in the unit; Figs.6 and 7 are sectional and plan views of another valve part of the valve mechanism in the unit; Figs. 8-10 are schematic views illustrating the flow of fluid through the valve mechanism; Fig . 11 is a sectional view of a commutating valve arrangement of the unit; Fig. 12 is a sectional view taken approximately along the line 12-12 of Fig 11; Fig. 13 is a schematic view of another control unit; Fig. 14 is schematic view of yet another control unit; Fig. 15 is a schematic view taken approximately along the line 15-15 of Fig. 14; Fig. 16 is a schematic view taken approximately along the line 16-16 of Fig. 14; Fig. 17 is a schematic view of a control unit embodying the present invention; and Fig. 18 is a view taken approximately along the line 18 - 18 of Fig. 17.

Referring to the drawings. Fig. 1 illustrates a control unit 10 which for purposes of illustration is used in a steering control system for steering a vehicle. However, as noted above the control unit may be applied to a variety of alternative different uses.

The control unit 10 includes a housing 11 into which a steering shaft 12 of a vehicle extends.

At the outer end of the shaft 12 a steering wheel 13 is connected so that upon turning of the -541854 steering wheel the shaft 12 likewise turns and the control unit 10 is operated to direct steering control fluid to a steering motor 14 which is suitably connected to effect power-assisted steering of the wheels of the vehicle. The interconnection between the motor 14 and the mechanism of the vehicle for effecting steering thereof will not be described, since such is conventional and known.

As shown in Fig. 1 the housing 11 includes two outlet ports 20,21, respectively, which are connected to opposite sides of the motor 14 so that when fluid flows from those outlets, the fluid flows into one or the other of ends of the motor 14. in addition, the housing 11 includes an inlet port 22 which is connected to an engine-driven pump 23. The housing also includes an outlet port 24 which is connected to a fluid reservoir 27.

The control unit 10 functions so that when no steering of the vehicle is occurring, fluid is directed by the pump 23' into the inlet Port 22 in the housing 11 and from the outlet port 24 to the reservoir in a continuous manner. However, if the operator is turning the sheering wheel, the unit 10 operates to direct fluid from the inlet'ports 22 to one or the other of the outlet porta 20, 21 depending upon the direction of tuning of the steering wheel. . The other of the outlet ports 20,21 is connected with the outlet port 24 so that fluid therefrom is directed to.the reservoir 27.

As shown in Fig. 2 the housing 11 of the control unit 10 includes housing portions 25, 25a. The housing portion 25 has a projecting portion 26 into which the steering shaft 12 extends. A suitable seal and bearing arrangement generally designated 27, is associated with the housing portion 26 and the shaft 12 so -.as to support the shaft 12 for rotation relative to the housing and prevent any leakage of fluid along the shaft 12. The shaft -641854 terminates in a chamber 29 in the housing portion 25 and specifically a flange portion 30 of the shaft 12 is located in the chamber 29, Suitable axial thrust bearings 31 are Interposed between a radial face of the flange portion 30 and a radial surface of the housing portion 25, as shown in Fig. 2.

A fluid metering means, generally designated 35, is located in the chamber 29. The metering means 35 comprises a gerotor gearset which includes an outer member 36 which has internal teeth thereon and an inner member 37 which has external teeth thereon. The teeth 10 of the members 36, 37 are intermeshed, as best shown in Fig. 3. The metering means 35 may be of conventional construction , The gerotor member 36 is supported for rotation about an axis coextensive with the axis of rotation of the shaft 12. In addition, the outer gerotor member 36 is secured to the flange portion 30 of 15 the shaft 12 by means of a plurality of suitable screw fasteners 40a so that upon rotation of the shaft 12 the outer gerotor member 36 is likewise rotated about the axis of rotation of the shaft 12. The initial rotation of the outer gerotor member 36 with the shaft 12 effects rotation of the rotor member 37 about its own axis. After the rotor member 37 rotates through a. small angle of rotation about its own axis, it is restrained from further rotation about its own axis, and thus on further rotation of the member 36, the member 37 orbits about the axis of rotation of the member 36, all of which will be described in greater detail hereinbelow. Of course, as the rotational and orbiting relative movement of the members 36, 37 occurs, the pockets which are defined by lobes of the members 36, and which are designated A—I* in Fig. 3 expand and contract.

The rotor member 37 is mechanically connected by a drive link to a valve mechanism, generally designated 41. The valve mechanism 41 is constructed to direct fluid flow to the steering motor 14 when actuated from a neutral condition. in its neutral condition the valve mechanism 41 directs fluid from inlet port 22 £o the outlet port 24 When actuated, the valve mechanism 41 directs flow from inlet .port 22 < ' ' to eitner Outlet 20 or 21 -and connects the other outlet port 20 or 21 to outlet port 24, depending on the steering direction. The valve meohanism 41 is actuated through the drive link 40 by the initial slight rotation of the rotor member 37.

The valve mechanism 41 is located in the housing portion 25a of the unit 10,. The valve mechanism 41 comprises an outer sleeve valve member 42 (see Fig. 2) whioh is rigidly and fixedly secured in a suitable manner in the housing 11, and a second or inner sleeve valve member 43 . which is fixedly and rigidly secured to the outer sleeve valve member 42. The two valve members 42, 43 since they are assembled to gether in a fixed relationship and are fixed within the housing 11, may be considered to be a single valve element and could be so cons tructed.

The valve mechanism 41 further includes a movable valve member which- is designated 44 and which is located within the valve member 43. The valye member 44 is supported for limited rotary movement Within the valve member 43 upon rotation of the rotor member 37.

The right end of the valve member 44, as viewed in Fig. 2, is mechanically connected by a connection 45 to one end of a commutator valve 101, to be described hereinbelow. Accordingly, upon torque being applied to the rotor member 37, the drive link 40 transmit· that torque to the valve member 44 through the commutator valve 101, and the mechanical connection 45. In the description below, the slots 43 are given the same reference number as the in the valve member openings in· the valve member 42 with which they communicate The outer member 42 of tlie valve mecnanism 41 is provided with a series of four annular grooves extending therearound and which are designated 50—53. The grooves 50—53 at various locations have openings provided therein for directing fluid flow radially inwardly, all of which will be described in greater detail below. The inner valve member 43 likewise has a plurality of slots therein, see Fig. 5, which extend axially, and underlie the plurality of the radial grooves 50—53. The mechanical connection 45 will not be described in detail, but in general it comprises a hollow cylindrical member which is keyed to both the commutator valve 101 and valve member 44 It does not interfere with fluid flow therethrough as will be apparent. The valve member 44, shown in Figs. 6 and 7, is provided with a series of lands and grooves which extend axially of the valve member 44.

As noted above, when no steering is occurring, the valve connections are such that fluid flows directly from the inlet port 22 to the outlet port 24 through fluid passageways in a manner which will be described hereinbelow. In addition, when the valve member 44 is moved due to rotation of the steering wheel, fluid flows from the inlet port 22 through the valve mechanism 41 and the metering means 35 and to one of the outlet ports 20 or 21 to one end of the motor 14. The return flow is from the other of the outlet ports 20 or 21 through the valve mechanism 41 and to the reservoir 1 27. Whether the flow is through the metering means 35 to the outlet port 20 or 21 depends upon the direction of rotation of the steering wheel 13. The detailed operation of the valve is best illustrated in schematic Figs. 8—10 which illustrate respectively the neutral position,a right turn position, and a left-turn position of the valve parts.

Fig. 8 specifically illustrates the flow through the valve - 9 413 5 1 mechanism 41 when the valve mechanism 41 is in its neutral condition. As noted above, the valve member 42 includes four annular grooves which extend circumferentially therearound and which are designated 50, 51, 52 and 53. Groove 50 communicates with the outlet port 24 and there are four radially extending passages 60 60a, 60b, 60c in valve menibet 42· which communicate with the groove 50. The annular groove 51 communicates with the inlet port 22 and there are four radially extending passages designated 61, 61a 61b, 61c in valve member 42 which communicate with the annular groove 51. The annular groove 52 communicates with the outlet port 20 leading to one side of the motor 14 and there are two radially extending passages '64, 64a ih the valVe member 42 which communicate with the groove 52. The annular groove 53 communicates with the outlet port 21 and there are likewise radially extending passage ’ *>3, 63a in the valve member 42 which communicate with the annular groove 53.

In addition, the space in the sleeve assembly designated 69 communicates with one side of the metering means 35, as will he described in detail hereinbelow. To provide for this Communication, the inner valve member 43 includes two radial openings 62, 62a which communicate fluid to the space 69. In addition, the valve member 44 is provided with an axial passage 65 which communicates with the other side of the metering means 35 and radial passages 66, 66a therein communicating with the axial passage 65.

As shown schematically in Fig. 8, when the valve member 44 is in its neutral position, lands, 70, 70a, 70b, 70c are located adjacent the passages 6i, .61a, 61b, 61c, respectively. The lands 70, 70a, 70b, 70c do not block flow of fluid from the-passages 61, 61c into grooves 72, 72a, 72b, 72c in the valve member 44. The grooves, 72, 72c communicate with the passage 60 and the grooves 72a, 72b, communicate with the» passage 60b . Accordingly, when the valve member 44 is in its neutral position, the flow of fluid from the passage gi—6ic is directed through the valve mechanism 41 to the outlet port 24 and to the reservoir 27. Thus, the valve mechanism may be termed open center. It should be clear, however, that a closed center valve could also be utilized in the system. The other . passages 60a and 60c communicate with grooves 74, 74a in the valve member 44 which are adjacent the passages bua, 60c but are blocked by the adjacent lands from communicating with adjacent ports.

Moreover, in the neutral condition of the valve parts, as shown in Fig. 8, the openings 62 and 62a which communicate with the metering means are also in communication with grooves 75, 75a respectively, in the outer periphery of the valve member 44.

The grooves 75 and 75a are located so as to provide communication With, passages 63, 63a in the valve mechanism 41. The· passages 63, 63a, of course, communicate with one end of the steering motor 14. Moreover, the passages 64, 64a, when the valve member 44 is in its neutral condition as shown in Fig. 8, are located immediately'adjacent lands 77, 77a, respectively, in the valve member 44. The lands 77, 77a are likewise constructed so as not to block communication between the passages 64, 64a and the passages 66, 66a, respectively, in the valve member 44. Thus, when the valve member 44 is in its neutral condition, the opposite ends of the steering motor are connected across the metering means 35 providing an open cylinder system. This construction permits the transmission of any forces which are applied to the wheels of the vehicle to be transmitted back through the hydraulic fluid in the system to the metering means . 35, tending to cause the metering means to operate as a motor. This provides a feel to the operator of any such forces.

As noted above, the valve member 44 is moved or rotated from its neutral position in response to rotation of the steering wheel to direct fluid to the steering motor 14 for purposes of steering. Moreover, as noted above, the valve member 44 is rotated due to torque applied thereto through the rotor member 37 and the drive link 40. As should be apparent to those skilled in the art, the rotor member 37 is rotated due to forces which act on the rotor member 37 upon rotation of the steering wheel. These forces involve a mechanical or gear reduction due to the fact that the rotor members 36, 37 have a geared interconnection therebetween. However, the pressure across the .metering means greatly affects the torque applied to the rptor member 37. If there is a low fluid pressure across the metering means ' . 35 due to a low differential fluid pressure across the steering motor, the torque applied to rotate the valve member 44 is substantially lower than when there is a high differential pressure across the steering motor. Thus, the torque applied to the valve manlier 44 is a function of the pressure required to operate the steering motor.

In this connection, the valve member is actually torqueresponsive and the torque which can be applied to the valve member 44 through the metering, means 35 from the steering wheel 13 is proportional to the fluid pressure in the metering means which in turn is responsive to the pressure differential across the steering motor. The greater the torque applied to the steering wheel, the greater the torque applied to the valve member 44 and the farther the valve member 44 will rotate.

In the event high torque is applied to the valve member 44 in one direction, the valve member 44 may move to its extreme position - 12 418 3 1 in that direction wherein surface portions 80 of the valve member engage surface portions 81 of the valve member 43. If the rotation of the rotor member 37 is in the opposite direction, again the valve member 44 can only rotate until surfaces 80a of the valve 5 member 44 engage the surfaces 81a of the valve member 43 As can be viewed in Fig. 4, the amount of rotation of valve member 44 which can occur is very slight and is designated X in Fig. 4, Once the surface portions 80, 81 or 80a, 81a engage, further rotation of the valve member 44 is positively prevented. In many steering 10 conditions, the torque applied to the steering wheel by the operator will be of a magnitude where the valve member 44 rotates a very slight increment less than its full capability for rotation. Thus, the valve member 44 in many steering conditions will move to an intermediate position rather than to a full indexed position wherein the stops 80, 81 or 80a, 81a engage.

Accordingly, for purposes of steering, the valve member 44 will take a position in which it divides the flow of fluid from the passages 61—61c between the passages 60, 60b, on the one hand, and the metering means 35, on the other hand. 2D For example, if the valve member 44 is rotated in a clockwise direction, as viewed in Fig. 8, to a very slight extent such that communication between the passages 61 - 61c and passages 60, 60h is not blocked off, it should be clear that there will be a pressure increase in the passages 61—61c. This will be due to the fact that the flow area of communication between the' passages 61 - 61c.and.the passages 60, 60b decreases. At the same time; passages 61a, 61ca will communicate with passages 66, 66a, respectively, in the valve member 44 for directing fluid to the metering means . 35. Also, the area of communication between openings 62, 62a and the passages 63, 63a respect30 ively, will increase so that fluid will be directed from the metering means 35 througn tne passages @3, 63a and to one side of the steering motor. The opposite side, of the steering motor will be connected to a tank (not shown) clue to the facp tnat passages 64, 64a will communicate with the tank tnrough passages bua, 60c in the valve mechanism. As a result, the flow from the inlet pressure passages'61 - 61c will he divided de5 pending upon the amount of rotation of the valve member 44. This provides for a pressure build-up in the steering motor 14 which is proportional to the amount of rotation of the valve member 44, and the valve member 44 moves in proportion to the torgue applied to the steering Wheel providing an effective follow-up steering System with a smooth pressure build-up in the steering motor 14 to effect Steering rate proportional to the rate of rotation of the steering wheel.

In the event that the valve member is rotated in a counterclockwise direction, as viewed in Fig. 8, the pressure directed to the valve member between passages 61 - 61c may again, be divided in much the same manner as that described above, except for the fact that the fluid is directed through the valve mechanism to the opposite end of the steering motor. In the event the direction of rotation is counterclockwise of the valve member 44, pressure < '· ' in the passages 61—61b is. directed to the metering means , 35 through ports 62, 62a and the flow is from the metering means through passages 64, 64a to one end of the steering motor .14._ The opposite ends of the steering motor are connected to a tank (not shown) by connection of passages 53, 63a with passages · 60a, 60c, respectively.

Again, in this mode of operation the flow being divided between the outlet and the steering motor, a smooth increase in the buildup of fluid pressure in the steering motor is provided in a manner which is proportional to the torgue applied to the steering wheel. in the event that the member 44, as shown in Fig. 8, is moved or rotated in a counterclockwise direction from the position shown in Fig. 8 to the position shown in Fig. 9, the inlet flow is no longer divided as described above. As shown in Fig. 9, the inlet fluid flow which flows into the valve from the pump 23 into passages 61, 61b flows to the metering means 35 through openings 62, 62a. Flow from the metering pump flows axially through the internal passage 65 of the valve member 44 and tjien radially througn passages 66, 66a and into passages 64, 64a, to one side of the steering motor 14. The flow from the other side of the steering motor 14 is through the conduit, into the housing through the port 21, through the -passageways 63, 63a, and through the Λ passages 60a, 60c, respectively, to the reservoir 27. In this manner, the fluid flows from pump 23 through the valve mechanism 41 to the metering -means 35 and through the metering means 35 back through the valve mechanism 41 to the steering motor 14 to effect steering of the vehicle.

In the event that the valve member 44 is rotated from its ’Fig. 8 position, clockwise as viewed therein, from the position shown in Fig. 8 to the position shown in Fig. 10, the vehicle is steered in an opposite direction as compared with Fig. 9. As shown in Fig. 10, when the valve parts are moved to such position, the fluid flow is from the inlet passages 61a, 61c through the passages 66, 66a and axial passage 65 in the valve member 44 to the metering means . The flow from the metering means 35 flows through the openings $2, 62a and through the -passages 63, 63a to one end of the steering motor 14 to effect steering of the vehicle in a direction opposite the direction of steering in Fig. 9. The flow from the other end of the steering motor is through the port 21, the passages 64, 64a and through the passages 60a, 60c which are connected to the reservoir 27. Accordingly, it should be clear that depending upon the direction of rotation of the valve member 44, the vehicle will be steered in a respective direction.

Figs. 8, 9 and 10 are somewhat schematic and exaggerated in order to show the schematic operation of the valve mechanism 41, whereas Figures 4 to 7 show detailed views of the structure of the valve mechanism providing the flow described in connection with Figs. 8 to 10. The reference numbers shown on the detailed Figures to 7 correspond with the schematic views shown in Figures 8 to 10.

» As is known, a commutator valve metnber . is utilized with gerotor gearsets for controlling the flow of fluid into and from the metering weans 35 The commutator valve meriier which may be utilized in the control unit may take a variety of different constructions , and any type of commutator valve member · may be utilized Which provides for the flow of fluid from the valve mechanism 41 to the metering means, and from the metering means back through the valve mechanism.

As shown in Figure 2, the flow from the valve mechanism 41 to theametering means and from the metering means 35 back to the valve mechanism Ls effected through a commutator valve member 101 and a manifold member 102. The manifold member 102 has a plurality of angled passages 103 for directing flow into and from the expanding and contracting pockets of the metering means 35 respectively. The manifold member 102 also includes a plurality of openings 103a throuch which the screw fasteners 40a extend. The face of the manifold adjacent the gerotor includes a plurality of openings where passages 103 intersect that face of the manifold member 102 for directing to or from the gerotor. Rigidly secured abutting the manifold member 102 is a plate member 104. The plate member 104 also has a plurality of openings for receiving the screw fasteners 40a.

The plate member 104 also has a plurality of openings 106 which align with the passages 103 in the face of the manifold - 16 418 54 member 102. The member 104 has an internal diameter which is substantially smaller than the internal diameter of the manifold member 102 and is provided in order to seal the metering means a suitable seal is provided between the face of the commutator valve member 101 and the radical face on the member 104 adjacent its internal diameter.

The commutator valve member 101 is located within a bore 110 in the manifold member 102, ( See Figs. 11, 12). The outer periphery of the commutator valve member 101 is provided with a plurality of axial slots which are designated 111.

There are six axial slots in the outer periphery of the member 101 in the embodiment disclosed. The axial slots 111 communicate with the space 69 located radially outwardly of the valve member 103. The cummutator valve member also'lias interposed between tne radial slots a plurality, again six in number, of radially extending passages 112 which extend into the interior of the commutator valve member 101.

As noted above, the manifold member 102 has a plurality of passages namely, seven in number, which are designated 103.

These passages 103 extend angularly through the manifold member 102 and intersect the radial face of the manifold member as well as the axial bore 110 therein. The openings provided by the passages 103 within the bore 110 are spaced circumferentially around the bore 110.

From the above, it should be apparent how the commutator valve member works. It should be clear that the manifold member 102, the plate member 104, and the outer gerotor member 36 rotate as a unit with the steering shaft 12. It should be further apparent that as the manifold member 102 rotates relative to the commutator valve member 101 the axial passages 103 sequentially -1741854 come into communication with the axially extending slots 111 in the outer periphery of the commutator valve member 101 and the radially extending passages 112 in the commutator valve member 101.

As a result, the proper commutation of fluid flow is provided by the commutator valve member.

Accordingly, as a result, fluid may flow to the metering means 35 from the space 69, through the axially extending slots 111 in the commutator valve member the angled passageways 103, the openings 106 in the member 104, and into the expanding passages of the metering means The flow from the contracting passages of the metering meaad 35 would be through openings 106 in the plate member 104 which Communicate with the contracting chambers of the metering means passages 103 in the member 102 and radial passages 112 in the commutator member 101, into the interior of the commutator valve member 101. The fluid may then flow axially through the interior of the mechanical connection 45 and into the axial passageway 65 in the valve member 44. Of course, in the event that the metering means • rotates in a reverse direction, the flow would be reversed from that described immediately hereinabove,. namely, the flow would be from the axial passageway 65 in the valve member 44, through the passages 112 in the commutator valve member 101, through the angled passages 103 in the manifold member 102, openings 106 in the member 104, and into the expanding chambers of the metering means In this case, the flow from the contracting chambers of the metering means Would be through the openings ^06 of the member 104 , into passages 103 of the manifold member 102, through axial slots 111 in the outer periphery of the commutator valve member-101, and into the space 69 adjacent the outer periphery of the valve mechanism 41.

From the -description hereinabove, it should be apparent that upon rotation of the steering·wheel, the valve member 44 is moved slightly in order to effect communication of the various ports in the valve mechanism and the proper actuation of the steering motor 14. The movement of the valve member 44 by the -metering means 35 is effected against the bias of a suitable spring means, generally designated 120. The spring means in the embodiment shown comprises a tcrsion bar 121 which is suitably secured at one end by a screw-and-nut assembly 122 to the housing of the control unit and is secured at the other end by a pin-and-slot connection, generally designated 123, to the valve member 44. It should be apparent of course, that upon rotation of the valve member 44, the rotation is in opposition to the force applied to the valve member by the torsion bar 1Z1 and that when that force is removed as by removal of the steering force applied to the steering wheel of the vehicle, the torsion bar 121 will effect a return of the valve member 44 to its neutral position. Of course, while a torsion bar spring centering mechanism is disclosed in the specific embodiment, any such biasing arrangement may be utilized in order to provide for a neutral positioning of the valve member 44. The torsion bar extends into the interior passageway 65 of the valve member 44 but it does not detrimentally affect fluid flow therethrough.

From the above description, it should be apparent that there is no rotary or rotating valve in the control unit which rotates at all times upon rotation of the steering wheel. The valve member 44 rotates for a small increment of movement and no more rotation thereof occurs while steering of the vehicle is being accomplished. Moreover, it should be clear that the steering shaft does not extend into the valve member 44 and has no mechanical interconnection with the valve member 44 except through the metering means 35, aa specifically described above. As a result, there is no need for a large package size in order to accomplish a mechanical interconnection of the steering shaft to a rotating valve member. As a result the diameter of the valve members 42—44 may be quite small.

Moreover, it should be clear from the above that initial rotation of the steering shaft causes actuation of the valve menher in order to port fluid through the metering means 35 and from the metering means to the steering motor in a proper follow-up manner.

Also, it should be clear that in the event that the powersteering pump 23 should not operate properly, the turning of the steering wheel will still cause actuation of the valve member 44 through the metering means 35 and that on further rotation of the steering shaft the metering means 35 will operate as a pump meohanism to force fluid through the system and still operate the steering motor 14, even though the power-steering pump 23 may be inoperative.

Furthermore, all of the advantages of feel of the road in both a nonsteering condition and a steerinq condition are effected and provided by the disclosed control unit . Accordingly, the control unit , described hereinabove, has all of the advantages of present and known control units . but yet is a substantial improvement over known, systems in that the cost of manufacture and the simplicity of construction are substantially improved and problems of leakage and package size are minimized.

Fig. 13 illustrates another control unit which is constructed similarly to that described hereinabove and uses a valve meohanism Similar to that described above, although the structure of the gerotor commutator arrangement is slightly different. In the control unit of Fig. 13, the steering shaft 150 is drivingly connected bv a pin connector 151 to the rotor or outer member 153 of a metering means The inner rotor member 154 of the metering means is drivingly interconnected with a drive link 155. The drive link 155 in turn is drivingly connected with a part which may be integral with the valve mechanism or drivingly connected therewith. That part is designated 156. In the embodiment shown, the commutation is through a plate-type valve, generally designated 160, the commutator valve 160 is suitably keyed to the rotor member 154 by a sleeve connector 161 so as to rotate and orbit with the rotor member. The commutation is generally similar to known structures and therefore will not be described in further detail. The plate 162 which is interposed between the housing and the commutator plate 160 functions to project radially inwardly to provide a proper seal for the commutator plate.

Figs. 14, 15 and 16 illustrate a still further control unit which is somewhat similar to the control unit of Fig. 13, except that as opposed to a rotary valve or axial valve of the type shown in the unit of Figs. 1—12, the valve of Figs. 14—16 is of a plate type.

In the control unit of Figs. 14—16, the steering shaft 200 is drivingly connected to the outer rotor member 201 of a gerotor gearset which in turn drives the inner rotor member 202 of the gerotor gearset. The inner rotor member 202 is drivingly connected through a link 203 to a plate valve member 204. The valve member 204 will rotate upon rotation of the steering shaft, muoh as the valve member 44 rotates, and a suitable stop pin, shown in Fig.,15. and designated 205, will engage a surface of the valve member 204 to prevent excessive rotation of the valve member 204 in any direction upon high torgue being applied thereto. The commutator valve member 206 is similar in construction and operation to that of the unit Fig. 13 and will not be described in detail, since it is generally of conventional construction.

As best shown in Fig. 16, the housing 210 which contains the control unit has an inlet port configuration which includes a generally arcuate U-shaped portion 211 which communicates with the inlet pump and which may be termed an inlet pressure port. A return reservoir port which is generally designated 212 includes a portion 212a which is interconnected by an arcuate portion 212b with a portion 212c which is diametrically opposed to the portion 212a. Also, on the housing there is a port 214 which communicates to one end of the steering motor and a port 215 ·. which communicates to the other end of the steering motor.

The valve member 204 which engages with the face of the housing, as shown in Fig. 15, includes a pair of ports 220, 221 which, when the valve is in neutral position, provides for communication between the inlet pressure port 211 and the outlet reservoir port 212. Accordingly, when the valve is in its neutral position, the flow pf fluid is from the pressure pump through the valve mechanism to a tank.

In the event that the valve member shown in Fig. 15 is moved in one direction relative to the housing 210, a port 230, which communicates to one side of the matering means , will move into communication or greater communication with the port 211 so that pressure is thereby ported to the metering means At the Same time, the other Side of the metering means , which Communicates with port 231, will communicate with the port 215 to direct flow to one end of the steering motor. The flow from the other end of the steering motor will return from port 214 to the outlet port 232 and will be communicated to outlet port 212c.

In the event that the valve plate 204 is rotated in a reverse direction, the port 231 will communicate with the inlet pressure port 211 and fluid will be ported to the metering means in a reverse direction from that described above through the port 231, flow from the metering means will come through the port 230 through port 214 to one end of the steering motor. Flow from the other end of the steering motor will be through port 215 and into the outlet 232 which communicates with the port 212c to port the fluid to the reservoir.

Accordingly, it should be clear that the control unit shown 10 in Figs. 14, 15 and 16 is similar in operation to that, described above, but rather than having a sleeve-type axial valve system, it is provided with a plate-type valve.

Moreover, the valve construction can be such that the proper intermediate positions of the valve are provided in order to operate in precisely the same manner as that described above in connection with the oontrol unit of Fig. 1 and that detailed description will not be made herein in view of the fact that it would merely involve redundancy.

It should be clear that the control units described may include different 2o types of commutation as well as different types of valve constructions.

Figures 17 and 18 illustrate a modification to the above described units, which forms an embodiment of the present invention. In the control unit of Figs. 17 and 18, the steering or input shaft 400 is drivingly connected through a gear interconnection to a drive sleeve member 401, the drive sleeve member 401 coaprising a' tubular member having integrally formed Internal gear teeth 402 (as best shown in Figure 18) and the shaft 400 including a drive plate fixed for rotation therewith and having integrally formed external gear teeth in meshing engagement with gear teeth 402. The gear teeth 402 also mesh with gear teeth 403 on the outer peripheral surface of the internally toothed outer rotor member 404 of the metering means , The externally toothed inner rotor member of the . metering means is designated 405 and is mounted for limited rotation about an axis coaxial with the rotational axis of the shaft 400.

The initial rotation of the steering shaft 400 effects rotation of the outer rotor member 404 which in turn effects a rotation of the inner member 405 as in the units of Figs. 1, 13 or 14. The initial rotation of the member 405 effects limited rotation of either a valve plate in the unit of Fig. 14 or an axial-type valve, as in the unit of Fig, 1, or Fig. 13 to effect the proper porting of fluid by rotation of a shaft 407 connected with the valve. However, in the control unit of Figs. 17 and 18, the rotor member 405 can only rotate a limited amount and is also restrained from any orbiting movement. In this case, rotation of the steering shaft 400 causes rotation and orbiting of the rotor member 404 in a manner similar to that shown in U.S. Patent Specification No.3,443,478. The inner diameter of the drive sleeve member is greater than the outer diameter of internally toothed rotor memner 404 to enable the relative orbital movement to occur while meshing engagement of the drive sleeve gear teeth, and the gear teeth on the outer periphery of the rotor member 404 is maintained. The center of motor member 404 is offset from the center of the drive sleeve 401 and only a portion of the external gear teeth on the rotor member 404 engage the gear teeth on the drive sleeve as will be apparent from the drawings. In this unit the commutator member 410 is fixed to the rotor member 405 in order to provide the necessary and proper commutation as the rotor member 404 rotates and orbits. Details of the valve mechanism which may be associated with the structure of Figs. 17 and 18 will not be further described, since it would be the equivalent of that described above or obvious modifications thereof.

Claims (6)

1. CLAIM S:1. A control unit for controlling fluid flow to a fluid motor, said control unit comprising valve means for directing fluid to said fluid motor in response to rotation of an input shaft about an axis, said valve means comprising a fixed valve part and a movable valve part, said fixed and movable valve parts defining passages for directing fluid to said fluid motor upon relative movement of said valve parts a metering means for directing a metered flow of fluid to said motor through said valve parts upon rotation of said input shaft and including an externally toothed gear member supported for limited rotational movement and an internally toothed gear member supported for orbital and rotational movement relative to said externally toothed gear member, said internally toothed gear member having one more tooth than said externally toothed gear member and the teeth of said gear members defining fluid pockets which expand and contract on relative orbital and rotational movement of the gear members, commutator valve means for controlling fluid flow to and from the fluid pockets formed by the gear members, a drive sleeve member having a portion drivingly connected with said input shaft for joint rotation therewith about said axis, said drive sleeve member having internal gear teeth, said internally toothed gear member having external gear teeth around the periphery thereof in meshing engagement with said internal gear teeth of said drive sleeve, a mechanical connection for transmitting torque from said externally toothed gear member to said movable valve part to move same relative to said fixed valve part in response to rotation of said externally toothed gear member, the intermeshing gear teeth of said drive sleeve and said internally toothed gear member and of said internally toothed gear member and said externally toothed gear member being effective to rotate and orbit said internally toothed gear member and to rotate said externally toothed gear member to transmit torque to said movable valve part upon rotation of said input shaft.

2. A control unit as claimed in claim 1 wherein said drive sleeve member comprises a tubular member integrally formed with said internal 5 gear teeth and said input shaft has a fixed drive plate drivingly connected for rotation therewith and having external gear teeth in meshing engagement with said internal gear teeth on said tubular member.

3. A control unit as claimed in claim 1 or 2, wherein said 10 fixed ahd movable valve parts comprise plate valve members movable relative to each other upon transmission of torque from said externally toothed gear member to one of the plate valve members.

4. A control unit as claimed in any one of the preceding claims wherein said externally toothed gear member is mounted for limited 15 rotation about an axis coaxial with said axis of the input shaft and the inner diameter of Said drive sleeve'member is greater than the outer diameter of said Internally toothed gear member to enable said relative orbital movement to occur while the meshing engagement of said drive sleeve gear teeth and said gear teeth on the outer periphery of 20 said internally toothed member is maintained.

5. A control unit as claimed in any one of the preceding claims, wherein the center of the internally toothed member is offset from the center of the drive sleeve member and wherein only a portion of the external gear teeth on the periphery thereof is in meshing engage25 ment with the internal gear teeth of said drive sleeve.

6. A control unit as claimed in claim 1, and substantially as herein described with reference to Figures 17 and 18 of the accompanying drawings.