DE2448241A1 - CONTROL VALVE AND COMPRESSION SYSTEM - Google Patents

Description

10/08/74

CAM GEARS LIMITED

45 Wilbury Way, Hitchin,

Hertfordshire, England,

Great Britain

Control valve and pressure medium system

The invention relates to a pressure medium system and a control valve for this pressure medium system, in particular as part rack and pinion steering with power steering for a vehicle.

Bei.einem such a steering system is mounted a pinion located at the bottom end of a bearing at its upper end a steering wheel column, which meshes with the toothing of a toothed rod or steering lying to the longitudinal axis of the vehicle, which in turn at its two ends to the Tie rods to be steered wheels of the vehicle is articulated. When the steering wheel is turned, drives the pinion gears or the handlebar and the steerable wheels, usually the front wheels are turned. Furthermore , a pressure piston is attached or molded to the toothed or steering rod, which moves with the steering rod and thus controls a pressure medium for reaching a steering aid. This Druckkolberi is part of a hydraulic pressure medium system, which further consists of a pressure accumulator and a pressure medium cylinder for the pressure,

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the pressure medium piston is better. The pressure medium, a hydraulic fluid, is increased from the reservoir pumped to or into the pressure accumulator to keep the fluid pressure in the pressure accumulator at a predetermined level to keep. The pressure medium reaches the pressure medium cylinder from the pressure accumulator in order to generate the required power steering assistance to provide. In order to obtain a good effect, it is desirable that the pressure in the liquid in the pressure accumulator is held at the above-mentioned level.

An object of the invention is to create a pressure medium system and a control valve suitable for such a system, which are then suitable to relieve the pump contained in the system when the pressure in the pressure accumulator in a predetermined or selected control area falls.

This task is in one respect with a control valve having a valve body therein a tubular - cylindrical - Chamber and a piston slidable in the chamber, initially solved in that the chamber at one end has a Control opening of smaller cross-sectional area than the cross-sectional area of the chamber, an inlet opening and two Outlet openings that a plunger and a valve element has a sliding seat in the control opening and in the chamber, respectively form that Druckeleraente, such as a spring force to adjust the plunger and the valve element in a first, the control opening closing position and for establishing a connection are provided between the inlet opening and only the first outlet opening, and that the plunger and the valve element by means of pressure medium pressure at the control opening in a second position for opening the control opening and producing it a connection of the inlet opening with the second outlet opening are movable when the pressure medium pressure at the control opening reached a predetermined upper level.

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Next is after the. Invention made an arrangement in which the releasing movement of the valve element from the first Position due to the effect of the pressure in the middle of the pressure on the control opening on the plunger and the following movement due to the action of the pressure medium pressure at the control opening on the larger valve element can be generated. This ensures that when the plunger is lifted sufficiently far and the control opening are no longer closed, the pressure medium pressure acts at the control opening on the larger cross-sectional area of the valve element and thus a sudden movement. of the valve element takes place in its second position.

Embodiments of the invention consist in that the pressure elements Return the valve element and the plunger to their first position when. · The pressure medium pressure on the Control opening drops below a predetermined level, and / or that a drain path for draining in the area of the chamber is close the control opening enclosed pressure medium is provided to the second outlet opening, further that the connection of the Inlet opening with the first outlet opening during loading

movement of the valve element in the area between its first and its second position is maintained, and that the control valve is a check valve to prevent a Having pressure medium flow from the first outlet opening into the chamber when the pressure medium pressure at the control opening its predetermined upper level.

Other embodiments according to the invention consist in that a pressure medium path extends partially along the longitudinal extent of the plunger from the end of the valve element remote from the valve element Plunger extends to the outer sliding surface of the plunger,

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further in that the pressure medium path is in a recess which partially extends along the outer sliding surface consists, if necessary, that the pressure medium path consists of a first,

from the opposite end of the path in the plunger and at least a second path from the first path to the outer sliding surface of the plunger leading path, and finally that a throttle is provided in the first path is.

Another solution according to the invention consists in a pressure medium system, in which a pumping of a pressure medium from a reservoir to a pressure accumulator or back to the Reservoir is provided and the pressure medium system is dependent on the pressure medium pressure in the pressure accumulator Has control valve for directing the pressure medium from the pressure accumulator to the reservoir when the pressure in the Pressure accumulator reaches a predetermined level, and for guiding the pressure medium from the reservoir to the pressure accumulator, when the pressure in the accumulator reaches a predetermined lower pressure. . .

Further protection requests result from the description, the drawing and / or the description of the prior application in conjunction with the claims.

The invention is shown schematically and by way of example in the drawing. Show it:

Fig. 1 shows a control valve cut in one in its Longitudinal plane located

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Pig. 2 a pressure medium system as part of a steering system of a vehicle »with a control valve, similar to the control valve according to Fig. 1,

3 shows another control valve, sectioned in a plane located in its longitudinal axis, and

4 shows a pressure medium system as part of a steering system of a vehicle with a control valve according to Fig. 3

According to FIGS. 1 and 2, a control valve initially consists of a valve body 2 with a tubular cylindrical Chamber 4, such as a bore, an egg inlet port 6 and two. Outlet openings 8 and Io radially through the valve body are led. The outlet openings 8 and 1o * are in the direction the longitudinal axis to each other with spacing ^ the first outlet opening 8 arranged diametrically opposite the inlet opening 6. Of the ' Chamber 4 closes coaxially with a stepped breakthrough larger width, which engages through one longitudinal end of the valve body 2.

A piston 26 is slidably mounted in the chamber 4. Especially According to FIG. 1, the piston is provided with an end plate 28 and two annular grooves 36 on its outer surface and 38 attached so that three jacket sections 3o, 32 and exist, which slide and close to the wall of the chamber issue. Annular spaces 40 and 42 exist between the wall and the annular grooves 36 and 38. A groove 61 extends diametrically over the left end (the left end face) of the piston 26. An axial channel 62 leads through part of the

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Piston 26 and connects the groove 61 and - via a radial Kanaiabschnitt - the annulus 42 with each other.

A sleeve, a valve element 14 is slidably seated in the interior of the opening 12 with a stop opposite an annular surface 16. A plunger 44 with a smaller cross-sectional area than the jacket sections 3o, 32 and 34 is slidably seated of the sleeve 14. An end cap 17 with an O-ring in a circumferential Groove sits slidably in a central section of the opening 12. It engages over the rear or after outwardly facing section of the plunger 44. With a threaded cover 18 in the externally located with internal thread Section of the opening 12 is closed. It is used by resting on the end cap 17 to the latter and the plunger as well as the sleeve 14 positioning. An axial bore 20 in the plunger 44 opens into a flat cylindrical passage 22, which extends diametrically on the front face of the plunger 44. A slot 3 runs diametrically across the rear End face of plunger 44, radial slots 5 across the rear face of sleeve 14. End cap 17 and one in the middle of the opening 12 located step 25 enclose an annular chamber 7o, which is through one of the lateral surface The space 27 bounded by the sleeve and the partially bevelled inner surface of the end cap 17 is connected to the slots 5 is. The sleeve 14 defines a control opening 23 to the chamber 4 of a smaller cross-sectional area than they Chamber 4 has.

The outlet opening 8 is provided with a back consisting of a ball 64, a compression spring 65 and a threaded cap 66

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check valve in one of the outlet opening 8 adjoining Line 67 is provided so that pressure medium cannot flow back into the chamber 4 through the outlet opening 8. The chamber 7o is connected to the line 64 outside the check valve by means of a channel 68. The channel 68 runs approximately parallel to the chamber 4. The annular grooves 3o and 32 of the piston 26 are arranged at such a distance from one another that the inlet opening 6 remain connected to the outlet opening 8 in the entire range of movement "of the piston 26. A rod with a diameter slightly smaller than that of the bore 2o, it is slidably supported in the bore 2o.

A second stepped step, coaxial with the chamber 4 Opening 24 extends from the chamber 4 opposite the opening 12 to the outside. The breakthrough 24 has a larger diameter than that of the chamber 4 and it can be threaded at its outer end (Fig. 4). The opening 24 is - as not shown further - connected to the outlet opening 1o by means of a drain channel.

The assembly of the control valve takes place in such a way that first the piston 26 through the opening 24 into the chamber 4 is introduced until the end plate 28 strikes the step of the opening 24. The sleeve 14 or the valve element ih the opening 12, the plunger 44 is inserted into the sleeve 14 and the rod 85 is inserted into the bore 2o. Further ■ the end cap 17 is pushed into the middle section of the opening 12 and over the rear section of the sleeve .14 and threaded cap 18 screwed in to lock end cap 17, sleeve 14 and plunger 44 in position keep. A compression spring 48 is then inserted into the opening 24

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inserted and held there by means of a cover 5o provided with a sealing ring, this (according to FIG. 4) with can be designed with a thread. However, a snap ring can also serve as a holder (according to Pig. 1). By preloading By means of the compression spring 48, the piston 26 moves into the first position shown in FIG. 1 when the end plate 28 stops pressed or held at the inner step of the breakthrough 24.

According to FIG. 2 - a diagrammatic representation - a pressure medium system includes a control valve similar to that according to FIG. 1. This system contains pressurized oil as the working fluid. Of the The main difference between the control valves according to FIG. 1 and FIG. 2 is that the latter two parallel Has outlet openings 8 and 1o and that the control opening 23 and the outlet opening 8 with a pressure accumulator are connected by two completely burned lines 57 and 78.

Furthermore, according to FIG. 2, a storage container 52 is on the one hand over a pump 54 is connected to the inlet port 6 and, on the other hand, directly to the outlet port 1o. To a pressure accumulator 56, both the first outlet opening 8 and the control opening 23 are connected by lines 78 and 57, respectively. further springs at the outlet opening 8, but outside the check valve, from the line 78 a line 8o to - not shown - Supply of a pressure medium piston in the vehicle steering system.

In operation, when the fluid pressure in the accumulator 56 is at a predetermined low level, are the The piston 26 and the plunger 44 are held in the position shown in FIG. 1 by the compression spring 48, in which the

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outlet opening 6 and the outlet opening 8 are connected to one another to form the pressure accumulator 56, while the inlet opening 6 from the pump 54 to the outlet port 1o connected to the reservoir 52 by the jacket section 52 from each other are separated. The pressure medium is polarized from the reservoir 52 conveyed through the chamber 4 in the area of the annular groove 36 and the pressure force opens the check valve against the force of the spring 65. The pressure medium thus reaches the pressure accumulator 56 and the control opening 23 the control valve according to Fig. 1, the pressurized pressure medium, such as hydraulic oil, passes through the channel 68, the chamber 7o, the slots 5 and the slot 3. In the case of the control valve according to FIG. 2, the pressurized arrives Pressure medium through the control opening 23 from the pressure accumulator 56 through the line 78.

When the pressure medium pressure in the pressure medium accumulator and increases in the slot 3, the plunger 44 and are with the piston 26 - moved to the right in the drawing against the force of the compression spring 48.

The pressure medium flows from the slot 3 between the rod 85 and the inner wall of the bore 2o through into the passage 22. When the pressure medium pressure in the pressure accumulator has now reached a predetermined upper level, the piston is 26 - in the drawing - migrated to the right into its second position, in which the jacket section 32 to the right of the second Outer outlet opening 1o is and a connection of the inlet opening 6 via the annular space 4o in the annular groove 36 to the second outlet opening 1ο is established. When the piston is in this The second position is the annulus 4o with both

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Outlet openings 8 and 1ο in connection, with which a pressure drop occurs at the outlet opening 8. This will kick the ball 65 in the closed position and emptying of the pressure accumulator 56 into the storage container 52 is prevented. The pressure medium is now pumped from the storage container directly into the storage container when the pump 54 is unloaded. Then reached the pressure medium pressure in the pressure accumulator 56 in turn its lower predetermined level, the compression spring 48 pushes the Piston 26 and the plunger in their first position - Fig. 1 back. The pressure medium is then explained again in the above Pumped into the pressure accumulator 56. The control valve allows the pump 54 to be directed towards the reservoir 52 to relieve, .during the pressure medium pressure within its control range from a selected upper to a lower Pressure reached.

In particular according to FIG. 1; The releasing movement of the piston 26 from its first to its second position is effected by action of the pressure medium pressure from the pressure accumulator on the cross-sectional area of the plunger .44 in the passage 22 caused. When the plunger 44 has moved enough to allow the passage 22 to communicate with the chamber 4, the pressure medium can enter the chamber 4 and press against the piston 26 cross-sectional area which is larger than the cross-sectional area of the plunger 44. As a result of this measure, the piston makes 26 after a slight triggering Movement a rapid movement from its first to its second position, so that the pressure conditions in the pressure accumulator 56 can be addressed quickly.

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So that this rapid or sudden movement of the piston 26 does not take place too suddenly, the throughput of the Pressure medium to the piston 26 is limited by the rod 85 accommodated in the axial bore 2o. One for one favorable switching speed suitable flow speed and flow rate can be achieved in a simple manner by corresponding Matching the diameter (and length) of the rod 85 and the hole 2o "be selected."

During operation, a small amount of pressure medium passes between the inner wall of the chamber 4 and the jacket section 34 or its jacket surface through into the opening 24. This amount of pressure medium can be supplied by a pressure medium already mentioned above Drain channel to the outlet opening 1o are derived, in order to prevent the build-up of pressure in the opening 24.

When the piston 26 returns to its first position, it is not to avoid that a small amount of pressure medium in the space between the jacket portion 3o, the sleeve 14 and the plunger 44 is locked. So now this amount of pressure medium would make the stop of the piston 26 on the sleeve 14 impossible, it is provided that the enclosed pressure medium flow through the groove 61 and through the channel 62 into the annular space 42 and finally to the storage container 52 can get. In a right-hand position of the piston 26 and thus of the jacket section 32 for closing the outlet opening 1o the previously described drainage path is blocked in order to prevent a pressure loss at the left end of the piston 26 avoid. ·

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ORfGIfSiAL INSPECTED 509816/0328

A number of modifications are within the scope of the invention and features included. For example, the Ball 64 of the check valve instead of the compression spring 65 and the threaded cap 66 by means of a spring washer, a so-called Belleville washer be pressurized and held. Palis a limitation or control of the pressure medium flow by the plunger 44, the bore 20, the rod 85 and the passage 22 should not be used, this can also be done by and can be achieved by means of a recess in the lateral surface of the plunger 44, the recess in the direction of The longitudinal axis runs from the rear to the front end face of the plunger 44.

Like in Pig. As shown in Fig. 2, the control port 23 can have its own line to the pressure accumulator 56, and the channel must also not necessarily axially of the plunger 44.

As described above, the inlet port 6 is with the outlet port 8 is connected over the entire area in and between the first and second positions of the piston 26. In In the second position, however, the pressure medium flows back into the pressure accumulator through the non-return or spring-loaded device Ball valve blocked.

In Pig. 3 shows another control valve according to the invention, 4 shows a pressure medium system with such a control valve. This modified control valve is general the control valve of FIG. 1 similar, so that the same reference numerals are used for identical parts. The main one The difference is that the piston 26 after

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3 has dimensions through which in the second position by means of the jacket section 3o the first outlet opening 8 is shut off from the inlet opening 6. In this way, the check valve can be dispensed with.

As shown in FIG. 4, the piston 26 reaches an intermediate position on its way from the first to the second position, in which the jacket sections 3o and 32 separate both outlet openings 8 and 1o from the inlet opening 6. To do this an undesirable To prevent the pressure in the chamber 4 from rising, the pressure medium can flow from the inlet opening 6 through a line 6o and a check valve 58 reach the line 57. This shunt is only in the very short one Effective period of time when the piston 26 reaches its middle position. A noticeable increase in pressure in the accumulator can therefore not occur.

The two pressure medium systems described are part of a steering system of a vehicle. As indicated in Fig. 2, leads a line 8o from the line 57 to a pressure cylinder which is part of the steering system. According to Fig. 4 leads a line 61 from the pressure accumulator 56 to a pressure cylinder as part of a steering system.

In the examples it has been assumed that the pressure medium is a hydraulic fluid, but can as Pressure medium also a suitable gas can be used.

Claims: - 14 -

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Claims (14)

Patent claims; 1. Control valve with a valve body, in it a tubular - cylindrical - chamber and one in the chamber sliding piston, characterized in that that the chamber (4) at one end has a control opening (23) opposite the cross-sectional area of the chamber (4) smaller cross-sectional area, an inlet opening (6) and two outlet openings (8, 1o) that a plunger has (44) and a valve element have a sliding seat in which Control opening or in the chamber that pressure elements (48), such as a spring force for adjusting the plunger and of the valve element in a first position that closes the control opening and for establishing a connection between the inlet opening (6) and only the first outlet opening (8) are provided, and that the plunger (44) and the By means of pressure medium pressure at the control opening (23), the valve element is in a second position to open the control opening. (23) and establishing a connection between the inlet opening (6) and the second outlet opening (io) are movable when the Fluid pressure at the control port reaches a predetermined upper level; 2. Control valve according to claim 1, characterized in that an arrangement is made in which the triggering movement of the valve element from the first position by the action of the pressure medium pressure at the control opening the plunger (44) and the following movement due to the action of the pressure medium pressure on the control opening the larger-area valve element (14) can be generated. - 15 - 509816/0328 3. Control valve according to claim 1 or claim 2, characterized in that "» ' characterized in that the pressure elements (48) move the valve element (14) and the plunger (44) in their first position return when the pressure medium pressure at the control opening drops below a predetermined level. 4. Control valve according to one of claims 1 to 3, characterized in that the connection of the inlet opening with of the first outlet opening (8) during the movement of the Valve element (14) in the area between its first and its second position is maintained, and that the control valve has a check valve (65, 64) to prevent one Pressure medium flow from the first outlet port in the chamber when the pressure medium pressure at the control opening is at its predetermined upper level. 5. Control valve according to claim 4, characterized in that the check valve is a ball check valve. 6. Control valve according to claim 5, characterized in that the ball (64) 'is spring-loaded (65) towards the closed position. 7. Control valve according to one of claims 1 to 7, characterized in that that a pressure medium path extends partially along the longitudinal extent of the plunger (44) from the valve element (14) opposite end of the plunger extends to the outer sliding surface of the plunger. - 16 - j 609816/0328 8. Control valve according to claim 7, characterized in that the pressure medium path consists of a recess ″ extending partially along the outer sliding surface. 9. Control valve according to claim 7, characterized in that the pressure medium path consists of a first, of which remote end outgoing path in the plunger and at least a second, from the first path to the outer sliding surface of the plunger leading path composed. 10. Control valve according to claim 9, characterized in that that a throttle is provided in the first path. 11. Control valve according to one of claims 1 to 1o, characterized in that a drain path for draining in the area The pressure medium enclosed in the chamber near the control opening is provided to the second outlet opening (1o) is. 12. Control valve · according to claim 11, characterized in that the discharge path extends axially through the valve element. 13. Pressure medium system, characterized in that a pumping of a pressure medium from a reservoir (52) to a Pressure accumulator (56) or back to the reservoir (52) is provided, and that the pressure medium system is one of the Has pressure medium pressure in the pressure accumulator dependent control valve, for directing the pressure medium from the pressure - 17 - 509816/0328 Memory to the reservoir when the pressure in the pressure accumulator reaches a predetermined level, and for directing the pressure medium from the reservoir to the pressure accumulator when the pressure in the pressure accumulator reaches a predetermined lower pressure. 14. Pressure medium system according to claim 13, characterized in that the control valve is a control valve according to one of the claims 1 to 12 is. 509816/0328 Blank page