DE3006468A1 - DEVICE FOR PRESSURE CONTROL FOR A PRESSURE STORAGE - Google Patents

Description

ALFRED TEVES GMBH P 4872

Frankfurt am Main, February 4th, 198o

ZL / Ri / be

J. Beiart - 152

Device for pressure control for a pressure accumulator

The invention relates to a device for pressure control for a pressure accumulator, in particular for motor vehicles with a brake slip control device, the pressure accumulator being operated by a pump that can be switched off is fed and at least two consumers that have different minimum feed pressures for proper operation need, can be switched on to the pressure accumulator.

The problem with such a supply of different pressure medium consumers is that the lowest permitted storage pressure after the highest minimum feed pressure of all consumers that can be connected must be determined. The pump delivery will therefore be designed so that the pressure in the pressure accumulator do not fall below the required minimum pressure can. As a result, the pump delivery must be switched on relatively frequently, although the consumer is rarely put into operation with the highest minimum feed pressure.

Such pressure regulations are in the book by Dr.-Ing. Erwin Samal "Outline of practical control engineering", published by R. Oldenbourg, 1967. On page 135 a pressure regulator is shown which is dependent on of the pending pressure in a pressure accumulator

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switches the pump delivery on or off. As a further example, a water level regulator is shown on page 137, which regulates the height of a water level with the help of an electrical circuit in such a way that that when a predetermined minimum is reached, the pump delivery is switched on and the water level grows up to a predeterminable maximum, upon which the pump delivery is switched off.

Also in the manual "Vickers Handbuch der Hydraulik", 3ο 1966, pressure switches are shown in which a hydraulic Liquid acts on a piston that is movable against the force of a spring and after actuates a microswitch in a certain way. Such pressure switches can only be used for Switching on or off a system can be used, so that if a larger hysteresis is desired, a such a switch would have to be available in duplicate. Such hydraulic switches with adjustable The minimum switching pressure and the adjustable maximum switching pressure are described on pages 96 and 97.

However, the switching elements listed in relation to the prior art cannot regulate the pressure in all cases solve satisfactorily. Especially when several different consumers are connected to one pressure accumulator are, it is desirable to regulate the pressure in the pressure accumulator in such a way that only the minimum feed pressures of the connected consumers are guaranteed. Especially with brake slip control devices to control the pressure curve requires pressure medium that is under as constant a pressure as possible. However, the pressure accumulator simultaneously feeds hydraulic power assistance for actuating the

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Brake system, possibly even other hydraulic consumers. With the hydraulic brake booster will be sent to the. controllable pressure does not set such strict conditions for constant maintenance as this in the case of pressure medium, which is used to regulate the pressure curve for the brake slip control device, is required.

It is therefore the object of the invention to provide a device for pressure regulation of the type mentioned at the beginning to create, through which the provision of the necessary pressure medium for several consumers with different Minimum feed ~ press by means of a common pressure accumulator is possible and the necessary Energy for providing the storage pressure is reduced. In addition, the facility should be safe be in the mode of operation and simple in structure. This task is performed in a device for pressure control of the type mentioned at the outset, according to the invention, in that a switching device is provided is the one that falls below the lowest minimum feed pressure of a consumer, which is the lowest Forms the switching threshold, switches on the pump drive and when a maximum pressure is reached in the pressure accumulator, which forms the uppermost switching threshold and is at least equal to the highest minimum feed pressure of the other consumer is, the pump drive switches off and when the consumer is operating with the highest minimum feed pressure is raised to the level of the highest minimum feed pressure.

The arrangement according to the invention can for example be as follows be designed that a pressure sensor the storage pressure

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scans and supplies an electrical signal to an electronic control device, which is dependent on electronically formed switching thresholds controls the pump drive, with at least the lower switching threshold in Dependency of the switched-on consumers can be changed.

According to a preferred development of the arrangement according to the invention, the switching device consists of a first pressure sensor, which is acted upon by the accumulator pressure

3ο is hit, and a second pressure sensor, which is from Pressure applied to a return line of a consumer and an electrical switch, the switch being common to the first and second Pressure sensor is controlled. In this way, two different pressures from one switching device scanned and operated according to the pressure conditions of the switch. The preferred setup the two pressure sensors and their coupling is described by the features of claims 4 and 7. To the It is the determination of the hysteresis of the switching arrangement, i.e. the maximum distance between the switching thresholds It is expedient that the first piston and the second piston are connected to one another by a lost motion coupling and there is a friction member acting on the second piston. A particularly simple arrangement of the The friction member consists in that it is arranged in an opening in the housing of the switching device and is pressed radially against the lateral surface of the second piston by means of a spring.

So that with sufficient pressure in the pressure accumulator and simultaneous application of the pressure piston of the

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second pressure sensor, the pump drive is not switched on and the space limited by the pressure piston temporarily fulfills a storage function, the actuating element is connected to the pressure piston in such a way that that the pressure piston with a movement in the sense of turning on the switch via a spring on the Actuator and acts in reverse movement directly on the actuator. There is power the spring is greater than the frictional engagement between the friction member Jq and the second piston. The features of claims Io and serve to avoid jamming of the lever assembly.

An embodiment of the device according to the invention for pressure control is shown in the drawing and is explained in more detail below.

The drawing shows in section the housing 1 of a hydraulic / electrical switching arrangement 2, which is dependent on a microswitch 5 from the pressure in the pressure accumulator 3 and the pressure in the line 4 actuated, which electrically switches a relay 8 via electrical control lines 6, 7.

If the relay 8 picks up and closes the contact 9, the positive voltage is applied via the line 13 to the electric motor 1o, which in turn has a ground connection 14. The electric motor 1o put into operation in this way will drive the pumps 11 and 12 via a common drive, the pump 11 delivering pressure medium from the pressure medium reservoir 16 via the suction connection 15 via a hydraulic branching device 17 into the pressure accumulator 3. In the pressure line, a check valve 19 is provided, which opens against the pressure of the pressure accumulator 3 and thus ensures _f

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that if the pump 11 leaks, the pressure accumulator 3 cannot empty.

In order to filter out any dirt particles in the pressure medium, there is a filter 2o in the suction connection 15 intended.

Via a pressure line 21, the pressurized Pressure medium of the pressure accumulator 3 is supplied to a pressure chamber 22 of the electro-hydraulic switching arrangement 2. A further pressure line 23 branches off from this pressure line 21 to the consumers HV and AS.

In the pressure chamber 22, a first piston 24 is arranged, which has an end wall 25 of the pressure chamber with its im Diameter formed smaller portion 26 penetrates sealingly. Between the end wall 25 and the a spring 28 is arranged in the diameter of the largest section 27 of the first piston 24, the spring force of which the first piston 24 has to overcome when moving in the direction of the end wall 25.

The smaller portion 26 of the first piston 24 protrudes into a space 29 and ends in this space with a head 3o which has a larger diameter. In this Space 29 is a second piston 31 is arranged, which with its end face 32 play-free on a contact pin 33 of a microswitch firmly embedded in the housing 1 5 is present.

On the side facing away from the end face 32, the second piston 31 engages around the head 3o _# so that the first.

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Pistons 24 and the second piston 31 are in contact with one another in the rest position shown. The head 3o and thus the first piston 24 is movable relative to the second piston 31 by an axial play χ. These Interconnection of the first piston 24 with the second piston 31 in the sense of a lost motion clutch causes, as will be described later, a certain hysteresis of the monitoring switching arrangement. The second Piston 31, which can only move to a limited extent axially between the stops 34 and 35 ο, is moved radially by a acting on him friction member 36 loaded. This friction member is by a spring 37, which in a radial to the second piston 31 lying bore 38 is arranged, with a predeterminable force radially against the piston 31 held.

The manner of puncturing the part of the electrical / hydraulic switching arrangement 2 described so far is as follows:

The second KoI-2p is in the rest position shown ben 31 at the stop 35, the microswitch 5 is closed. The relay 8 is energized and thus the contact 9 closed, so there is electrical voltage on motor 1o. The pump 11 conveys pressure medium from the Pressure medium reservoir 16 in the pressure accumulator 3; the in Pressure accumulator 3 pending pressure is transmitted to space 22 via pressure line 21. The pressure in the room acts on the first piston 24 and moves it against the force of the spring 28 in the direction of the microswitch 5. If the axial play χ to the second piston 31 is overcome, the second piston 31 is removed from the first Piston 24 carried along and moved against microswitch 5. By the contact pin 33 is the so far

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closed contact of the microswitch open. By the interruption of the circuit of the relay coil • the relay 8 drops out, whereby the contact 9 opens and the "pump delivery is interrupted. The piston 31 will apply to the stop 34 when the final pressure has built up, the arrangement is now in a left end position, in which the pressure accumulator 3 is charged to, for example, 90 bar.

If the pressure slowly falls below 90 bar, the "spring." 28 move the first piston 24 to the right, so that its end face 4o from the end face 41 of the second Piston 31 will lift off. However, the second piston 31 itself will not move because it is through the friction member 36 is held in place. This' friction member 36 must be designed so that it the spring-loaded contact · 'Can hold pin 33 in its position.

If the pressure drops further, the spring 28 will move the first piston 24 further to the right, the head 3o approaches the stop 39 of the second piston 31. If the rear edge of the head 3o is in contact with the stop 39, then When the pressure is further reduced, the spring 28 follows the overall arrangement of the first piston 24 and the second piston 31 move to the right, the contact pin 33 of the microswitch 5 will follow this movement and the pump delivery will be switched on again. This could e.g. with a memory printer of approx. 7o bar the fall,

: '.: le L;.: r.-j.; \ c of the memory now takes place again up to 90 bar, ■: 1er head ic must finally the again created axial cT-i'V.'. ■ "ν'.ο. & - '" .- · "-.?: Cover face 4o to face 41 of - • 0 zve -_v2r>. Piston 3 ·. Only when this path 3 ¹ Ur ^1- U; '-Teleat it · ">? When printing, 5i ^: > h to c'.a ^h ir> to approx.

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Have increased 90 bar, the second piston 31 can be moved again for a further switching process.

The dead link from the second piston 31 and head 3o of the first piston 24 has the task of the width of the Hysteresis, in the case shown of approx. 20 bar, to be determined in conjunction with the spring 28 and the friction member 36. It is easy to see that with a once - constructed arrangement the hysteresis only through an appropriately selected spring 28 can be achieved.

This part of the switching arrangement 2 is a further part connected in parallel, which engages in a radial groove 43 of the second switching piston 31 via a lever 42. The lever 42 is rotatably mounted on an axle 44 which is fixedly arranged in the housing 1. That designed as a ball head end 45 of the lever 42 is arranged in the second piston 31 in such a way that the ball head 45 largely has its center point in the vicinity of the axis of the second piston 31 during a movement. The other end of the lever 42 is with an actuator

2q transmission member 46 in connection, which via a spring 4 8 on a pressure piston 47 is supported. Here, the actuating member 46 is let into the pressure piston 47 in such a way that that the spring 48 formed as a head end 49 in the pressure piston 47 against stops 5o des Plunger holds. The actuating member 46 has an oval opening 51 at its end engaging the lever 42, into which a pin 52 attached to the end of the actuating member 46 engages. The oval opening 51 ensures that with allowed axial movement of the loading

3 _Q actuating member 46 of the lever 42 and the axis 44 remains pivotable, 'without the arrangement can jam.

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The pressure piston 47 is sealingly displaceable in the housing 1, so that it separates a pressure space 53 from the rest of the pressure-free space 45. To also in the drawn rest position To have a defined pressure space 53 available, a stop 55 is provided in the housing 1, to which the pressure piston 47 rests in its rest position. In this rest position, the pressure piston held by a spring 56, which lies in an annular groove 57 in the pressure piston 47, and against each other a stop 58 is supported in the housing.

The space 53 is connected to a consumer via the line 4. The pump delivers via the suction connection 59 12 with the motor 1o switched on, the pressure medium from the pressure chamber 53 via a counter to the pressure of the pressure accumulator opening check valve 6o in the pressure accumulator The suction connection 59 is still via a check valve 61 is connected to the pressure medium reservoir 16. Here, the spring 62 of the check valve is designed in such a way that that a pressure of e.g.

can build up to a maximum of 2bar. Is via line 4. pressurized fluid fed in, so the return valve will open and the excess Pressure medium passed on to the pressure medium reservoir 16.

If one of the consumers A / S connected to line 4 switches on, it will, due to the Return of the pressure medium, build up a pressure of approx. 1 to 2 bar in the pressure chamber 53. Assuming. that at the time the consumer was switched on in the pressure accumulator 3 there was a pressure of approx. 8o bar, so the head 3o on the one hand to the end face 41 of the

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second piston 31 have a certain path, but on the other hand also to the stops 39 a certain distance Have game.

As a result of the pressure in the pressure chamber 53, the pressure piston 47 and the actuating rod 46 will move will move lever 42 and forward movement of plunger 47 will be via pivot 44 of the lever 42 converted into a backward movement on the second piston 31. However, since the ball head 45 of the lever 42

Ho has a slight axial play in the radial groove 43, the ball head 45 will come to rest on the side 63 of the groove 43 only after a slight forward movement of the pressure piston 47 and will now move the second piston 31 to the right with further movement of the pressure piston 47. This has the consequence that the switching area of the upper switching device is intervened and an immediate pump delivery is switched on by closing the microswitch 5.

In this case, not only the pump 11 is now pressurized medium promote the pressure medium reservoir 16 in the memory, but also the pump 12 will feed the pressure medium present in the pressure chamber 53 into the pressure accumulator 3.

The pressure in the pressure accumulator will now rise to 9o bar and at this moment the face will be 4o des Head 3o again rest on the end face 41 of the second piston 31 and this now against the force of the lever Move 42 to the left to switch off the microswitch again and interrupt the pump delivery. The pressure chamber 53 continues via line 4

3p pressure medium is supplied, so the pressure piston 47 is

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move further to the left, but do not now transfer its forward movement to the lever 42 can. In order to still be able to carry out a forward movement, the spring 48 is provided which compresses itself through the force on the pressure piston'47. The switching arrangement therefore not only has the Function of the pressure monitoring, the pressure chamber 53 also serves as a volume reservoir for the pump 12.

Is now in this position due to higher pressure medium requirements If the connected consumer drops the pressure in the pressure accumulator, the first piston 24 move away from microswitch 5 to the right again due to the force of spring 28. In this operating state however, the second piston 31 does not remain in it

J5 position pushed by the first piston 24, because the force of the spring 48 acts on the second piston 31 via the actuating member and the lever 42 and keeps it in contact with the head 3o. The microswitch will move to the right with a slight movement of the first piston 24 and will switch on again immediately; the . The pressure is immediately increased back to So bar.

The entire switching arrangement 2 thus has the following effect:

Under normal operating conditions, controlled by the first piston 24 and in the sense of a lost motion clutch on the first piston 24 attached to the second piston 31 in the pressure accumulator 3 pressure fluctuations to for example 2o bar approved. This is fully sufficient to supply the connected consumer H / V. Due to such a relatively large permitted hysteresis range, the motor is only rarely in operation

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taken. However, if the additional consumer A / S is switched on, this has a higher, considerably more constant pressure level required, the arrangement of pressure piston 47, actuating member 46 and lever 42 is the rest of the switching arrangement influence in such a way that the hysteresis range is reduced to a few bar (1 to 2 bar).

Such switching arrangements are particularly advantageous in vehicles with anti-skid control devices. as The first consumer H / V connected to the pressure accumulator 3 can provide a hydraulic brake booster be that allows relatively large pressure fluctuations. However, with the help of the pressure medium in the pressure accumulator 3 if an anti-skid control is intended, the accumulator pressure must be relative in order to ensure error-free control be constant. This can be done easily by the described embodiment of the switching arrangement according to the invention By dimensioning the spring 48, the increase in the switch-off threshold can be determined.

Of course, it is also possible to use the hydraulic modes of operation described here by means of an electromechanical To realize switching arrangement or by an electronic switching arrangement. These switching arrangements but would require a conversion of the hydraulic pressure signals into electrical signals, which in turn entails a certain amount of effort. The circuit arrangement described can be used without difficulty and without Use particularly large electrical outlay in any printing system that involves different consumers a pressure accumulator are connected and the various consumers here have different minimum feed pressures expect from memory.

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Claims (13)

ALFRED TEVES GMBH P 4872 Frankfurt am Main, February 4th, 198o ZL / Ri / be / ho. J. Beiart - 152 Claims (1. / device for pressure control for a pressure accumulator, especially for motor vehicles with a brake slip control device, the pressure accumulator being fed by a pump that can be switched off and at least two consumers that require different maximum feed pressures for proper operation can be connected to the pressure accumulator, characterized in that a switching device (2) is provided which, when the lowest minimum feed pressure of a consumer (H / V), which forms the lowest switching threshold, is undershot, switches on the pump drive (1o) and when a maximum pressure in the pressure accumulator (3) _{f is reached,} which forms the uppermost switching threshold and at least is equal to the highest minimum feed pressure of the other consumer (A / S), the pump drive (1o) switches off and when the consumer (A / S) is operated with the highest minimum feed pressure, the lower switching threshold for switching on the pump drive (1o) to the level of the highest minimum feed pressure raised wi approx. 130037/0084 P 4872 2. Device according to claim 1, characterized in that a pressure sensor shows the storage pressure scans and feeds an electrical signal to an electronic control device, which in Controls the pump drive (1o) as a function of electronically formed switching thresholds, whereby At least the lower switching threshold can be changed depending on the consumers (H / V, A / S) switched on is. 3. Device according to claim 1, characterized in that the switching device (2) from a first pressure sensor, which is acted upon by the accumulator pressure, and a second pressure sensor, from the pressure of a return line (4) of a consumer is acted upon, and there is an electrical switch (5), the switch (5) being common is controlled by the first and second pressure sensors. 4. Device according to claim 3, characterized in that g e k e η η 2o. records that the first pressure sensor is a first piston (24), which against the force of a spring (28) and with the interposition of a second piston (31) acts on the electrical switch (5), and the second pressure sensor a Has pressure piston (47) which is connected to the second piston (31) via a lever arrangement is. 130037/0084 P 4872 5. Device according to claim 4, characterized in that that the first piston (24) and the second piston (31) are connected to one another by a lost motion clutch and a friction member (36) is present, which acts on the second piston (31). 6. Device according to claim 5, characterized in that the friction member (36) in one Opening of the housing (1) of the switching device (2) is arranged and by means of a spring (37) radially against the outer surface of the second piston is pressed. 7. Device according to claim 4, characterized in that the lever arrangement has a pivotable lever (42) which with one end (ball head 45) into a radial opening (45) of the second Plunger (31) engages, and an actuator (46) connected to the pressure piston (47) and which is attached to the other end of the lever (42) is attached, comprises. 8. Device according to claim 7, characterized in that the actuating member (46) is connected to the pressure piston (47) in such a way that the pressure piston (47) when moving in the sense the switching on of the switch (5) via a spring (48) on the actuating member (46) and vice versa Movement acts directly on the actuator (46). 130037/008 P 4872 9. Device according to claim 8, characterized in that the force of the spring (48) is greater than the frictional engagement between the friction member (36) and the second piston (31). 1o. Device according to Claim 7, characterized in that the spherical head has a shaped end (45) of the lever (42) is arranged in the radial opening (43) with axial play. 11. A device according to claim 8, characterized geke η η - ^ q is characterized in that the pressure piston (47) is acted upon by a further spring (56) in the same direction as by the spring (48). .12. Device according to Claim 7, characterized in that the actuating member (46) has a pin (52) which engages in an oval opening (51) of the lever (42). 13. Device according to one of the preceding claims, characterized in that during operation of the consumer (AS) with the greatest minimum feed pressure the uppermost switching threshold for switching off the pump drive (1o) is raised. 130037/008 4 BATH ORIGINAL