JPH0228503B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention provides a quantity measuring device, an actuating mechanism and an adjustable feed throttle between the pump connection and the respective supply-side servomotor connection in conjunction with the quantity measuring device. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a servomotor, for example a servomotor in a motor vehicle steering system, which is provided with a quantity adjusting device in series with one another, in particular variable in the working direction.

Such control devices are available for example from Danfuoss.
Known for the OSPA and OSPB steering units. Its basic structure corresponds to that described in German Patent No. 1293029. That is, two concentric rotary slide valve sleeves are arranged in the casing bore,
One of the rotary slide valve sleeves is connected to the operating mechanism, whereas the other rotary slide valve sleeve is connected to the output hinge shaft of a gear motor, which serves as a quantity measuring device; A supply throttle, a return throttle, a diversion valve and a distribution valve for the gear motor are thus formed. The servo motor connection of this steering unit can be connected directly to both sides of the servo motor. The return action produced by the gear motor moves the servo motor in proportion to the amount of operation of the operating mechanism. If the pressure fluid (pressure oil) pump fails, the gear motor can act as an auxiliary pump, so emergency operation is possible. However, the amount of pressurized liquid flowing through the volume measuring device is limited and therefore the operating speed of the servo motor is limited.

In order to increase the operating speed of the servo motor,
It is known to connect two quantity measuring devices hydraulically in parallel and mechanically coupled to each other (DE 1901588 A1). In this case both quantity measuring devices act as measuring pumps. The supply and return restrictions are adjusted in relation to the measured pump pressure. In the event of a failure of the pressure liquid pump, the valve reacts and short-circuits one measuring pump, allowing manual operation of the other measuring pump, which now acts as an auxiliary pump. However, providing a second measuring pump in this way requires additional and expensive outlays. Furthermore, when operating the auxiliary pump during emergency operation, the friction and flow resistance in the inactive measuring pump must be overcome.

Furthermore, it is known (DE 29 32 847 A1) to connect a control circuit and a working circuit in parallel to each other in order to supply the servomotor with pressure fluid. In this case, a quantity adjusting device with a quantity measuring device and a feed throttle is provided in series with the control throttle in the control circuit. A non-return valve closing towards the pressure liquid pump, a pressure control valve and a working throttle are arranged in series in the working circuit. The control orifice and the working orifice are formed on a common spool and have open cross sections that are proportional to each other. The spool at the same time constitutes a pressure comparator which controls the pressure control valve, which keeps the pressure drop at the control throttle equal to the pressure drop at the working throttle. In this way, a significantly larger amount of pressure liquid can be supplied to the servomotor by means of a single quantity measuring device. This is because the amount of working pressure fluid flowing through the working circuit is proportional to the amount of control pressure fluid flowing through the control circuit. However, in this case an additional control throttle is required in the control circuit, which increases the pressure drop. Additionally, the pressure comparator spool must be configured to perform a total of three functions.

SUMMARY OF THE INVENTION It is therefore an object of the invention to improve a hydraulic control device of the type mentioned in the first place so that, despite its extremely simple construction, it can be used to The purpose is to make it possible to supply liquid to a servo motor.

In order to achieve this objective, the configuration of the present invention includes:
In the first-mentioned type of hydraulic control, the pump connection and the respective supply-side servomotor connection are additionally connected to each other by a booster line, which In series with each other there is a booster throttle which is mechanically connected to the throttle and is adjustable in proportion to the feed throttle, and a pressure control device which keeps the pressure drop across the booster throttle the same as the pressure drop across the supply throttle. I made it.

With this configuration, the quantity regulating device can be installed between the pump and the servo motor in the usual way. This is because the booster line is provided between the pump connection and the servo motor connection. The additional costs required to provide the booster throttle are very small. This is because the boosting orifice is mechanically connected to the supply orifice, so that it can be easily mounted on an adjusting member, such as a spool of a quantity adjusting device. Since the pressure control device only has to perform one function, it is also simple to construct. Therefore, the manufacturing cost of the entire control device according to the invention is low. Also,
A very precise control is achieved due to the fact that the supply throttle and the booster throttle are mechanically coupled to each other.

In one advantageous embodiment of the invention, the pressure control device has a throttle device connected to one side of the booster throttle, which throttle device is controlled by a pressure comparator, which pressure comparator is connected to one side of the booster throttle. The pressure on one side of the supply restrictor and the pressure on one side of the booster restrictor are loaded in opposite directions, and the other side of the feed restrictor and the other side of the booster restrictor are connected to each other. . By virtue of the fact that the supply throttle and the booster throttle are connected to each other on one side, it is possible to equalize the pressure drops in both throttles by comparing the pressures on the other side.

In this case, a throttle device controlled by a pressure comparator is connected upstream of the booster throttle, a quantity measuring device is connected upstream of the feed throttle, and in each case the servo motor connection on the feed side is connected to the feed throttle and booster. It can be connected to an aperture. This makes it possible to maintain the conventional structure of the quantity adjusting device with variable working direction, ie the quantity measuring device is connected upstream of the feed throttle.

Furthermore, it is advantageous to provide a non-return valve in the booster line which closes towards the pump connection. This check valve is open during normal operation, but is closed during emergency operation when the metering device is used as an auxiliary pump.

In the following, the configuration of the present invention will be specifically explained based on the embodiments shown in the drawings.

A pressure liquid pump 1 sucks liquid from a tank 2. In this case, the maximum pressure of the pressurized liquid is determined by the pressure relief valve 3. The quantity regulating device 4 has a pump connection 5 and a tank connection 6 as well as two servo motor connections 7 and 8. Servo motor connection parts 7 and 8 are connected to servo motor 1
1 to both pressure chambers 9 and 10.

The quantity adjusting device 4 has three throttles as is well known. In the situation shown, in which the piston of the servo motor 11 is moved towards the right, the throttle 12 serves as a supply throttle, the throttle 13 serves as a return throttle and the throttle 14 serves as a bypass throttle. The throttle 14 is bridged by a non-return valve 15 which closes towards the tank 2. These 3
The three throttles 12, 13 and 14 are jointly adjusted by a control device 16. In the control device 16, the position of the actuating mechanism 17 and the position of the measuring motor 18 are compared with each other. The measuring motor 18 is connected in series with the supply throttle 12 in a supply line 19 , and the return line 20 leads directly from the return throttle 13 to the tank connection 6 . In the neutral position, bypass throttle 14 is completely open, whereas throttles 12 and 13 are closed. In the illustrated state, the aperture is 1.
2 and 13 are fully or partially open;
Accordingly, the bypass throttle 14 is completely or partially closed. If the actuating mechanism 17 is operated in the opposite direction, the throttle 13 serves as a supply throttle and the throttle 12 serves as a return throttle. In this case, motor connection A of measuring motor 18 is connected to point C instead of point B of the circuit, and motor connection D is connected to point E instead of point C of the circuit. Furthermore, points B and F are connected to each other.

According to the invention, the quantity regulating device 4 is provided with an additional circuit part 21 . This circuit part 21 has a booster line 22 which is arranged between the pump connection 5 and one servomotor connection, in the illustrated state the servomotor connection 7. There is. The booster line 22 is connected to the pressure liquid pump 1
A check valve 23 that closes towards the end of the flow, a pressure control device 24, and a booster throttle 25 are provided in series with each other. The boosting aperture 25 has three apertures 12, 13 and 1
4. Mechanically coupled to 4. and booster aperture 2
The open cross-section of 5 is made to vary proportionally to the open cross-section of diaphragm 12.

The pressure control device 24 keeps the pressure drop across the booster throttle 25 the same as the pressure drop across the supply throttle 12 . For this purpose, a throttle device 27 is provided, which is controlled by a pressure comparator 26, which is configured as a piston. One end face 28 of the piston is loaded with pressure in a pressure chamber 29 connected to the supply conduit 19, and the other end face 30 is loaded with pressure in a pressure chamber 29 connected to one side (upstream side) of the booster throttle 25. 31 is loaded with pressure. A weak return spring 32 causes the throttling device 2 to close when no supply pressure is present.
Helps close 7.

When the operating mechanism 17 is operated in the opposite direction, the connection point G on the servo motor side of the booster conduit 22 is disconnected from the point H and connected to the point I. Furthermore, pressure chamber 2
9 is disconnected from point B and connected to point E. In this case, the throttle 13 serves as a feed throttle and the pressure drop across the booster throttle 25 is kept the same as the pressure drop across the throttle 13.

The quantity regulating device 4 works in a known manner. In other words, the amount of pressure liquid measured by the measuring motor 18 flows to the servo motor 11 . Since the pressure drop at the booster orifice 25 is the same as the pressure drop at the supply orifice 12 and the opening cross-sections of these two throttles are varied proportionally to each other, the pressure drop through the booster line 22 through the measuring motor 18 is A volume of pressure fluid flows that is exactly proportional to the volume of pressure fluid flowing. The servomotor 11 can therefore be operated at a significantly higher speed than is possible due to the amount of pressure liquid flowing through the measuring motor 18, and yet with very precise control.

If the pressure liquid pump 1 driven by the internal combustion engine fails, the measuring motor 18 can be activated as an auxiliary pump by actuating the operating mechanism 17. In this case, the pressure liquid is sucked in via the check valve 15, which acts as a suction valve.
The signal is sent to the servo motor 11. A flow of pressure liquid back into tank 2 via booster throttle 25 is prevented by check valve 23 . The boost ratio can be easily set to a desired value by selecting the cross-sectional ratio of the supply throttle and the boost throttle. In the actual structure, for example, the pressure control device 24 and the check valve 2
3, optionally together with a pressure relief valve 3, 1
They can be combined into one unit and mounted from the outside on the casing block of the quantity adjusting device 4 with the addition of the booster throttle 25.

In the illustrated embodiment, in the neutral position, the pump connection 5 and the tank connection 6 are connected to the bypass throttle 1.
4 (open center).
As an alternative to this, it is also possible for pump connection 5 and tank connection 6 to be disconnected from each other in the neutral position (closed center).
Furthermore, although in the illustrated embodiment the two servo motor connections 7 and 8 are disconnected from each other (non-reaction), they can also be connected to each other in the neutral position (reaction).
Furthermore, it is possible to carry out pump control related to the load pressure (load sensing) and/or braking taking into account external forces (power beyond).

[Brief explanation of drawings]

The drawing is a schematic illustration of one embodiment of the invention. 1... Pressure liquid pump, 2... Tank, 3...
Pressure relief valve, 4... Volume adjustment device, 5... Pump connection, 6... Tank connection, 7 and 8... Servo motor connection, 9 and 10... Pressure chamber, 11...
...Servo motor, 12-14...Aperture, 15...
Check valve, 16...control device, 17...operation mechanism, 18...measuring motor, 19...supply conduit, 2
0...Return conduit, 21...Circuit part, 22...Boosting pipe, 23...Check valve, 24...Pressure control device, 25...Boosting throttle, 26...Pressure comparator, 2
7... Throttling device, 28... End face, 29... Pressure chamber, 30... End face, 31... Chamber, 32... Return spring, A... Motor connection, B and C... Point, D...
...Motor connection part, E and F...points, G...connection points, H and I...points.

Claims (1)

Claims: 1. Between the pump connection and the servomotor connection on the respective supply side, there is a quantity measuring device and an actuating mechanism and an adjustable supply throttle associated with the quantity measuring device in series with each other. In hydraulic control devices for servo motors of the type with a quantity regulating device, the pump connection 5 and the servo motor connection 7 on the respective supply side are additionally connected to each other by means of a booster line 22. This booster pipe 22 is connected to the supply throttle 1
2 and a booster throttle 25 which is mechanically coupled to the feed throttle 12 and is adjustable in proportion to the supply throttle 12;
A hydraulic control device for a servomotor, characterized in that it has in series a pressure control device 24 for keeping the pressure drop at the same as the pressure drop at the supply throttle 12. 2. The pressure control device 24 has a throttle device 27 connected to one side of the booster throttle 25,
This throttle device 27 is controlled by a pressure comparator 26 which is loaded in opposite directions by the pressure on one side of the supply throttle 12 and the pressure on one side of the booster throttle 25. , supply orifice 1
2. The control device according to claim 1, wherein the other side of the booster diaphragm 25 and the other side of the booster diaphragm 25 are connected to each other. 3 throttling device 2 controlled by pressure comparator 26
7 is connected upstream of the booster throttle 25 , and a quantity measuring device 18 is connected upstream of the feed throttle 12 , in each case the servo motor connection 7 on the feed side is connected to the feed throttle 12 and the booster throttle 25 . The control device according to claim 2, which is connected to the control device. 4. The control device according to any one of claims 1 to 3, wherein a check valve 23 that closes toward the pump connection portion 5 is provided in the booster conduit 22.