JPH07101070B2 - Control device for electromagnetic proportional control valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for an electromagnetic proportional control valve, and in particular, controls dither applied to a valve element to an optimum frequency according to the temperature of hydraulic oil. The present invention relates to a control device for an electromagnetic proportional control valve whose operating temperature range is expanded.

(Prior Art) Conventionally, as a control device for this type of electromagnetic proportional control valve,
For example, the ones shown in FIGS. 4 to 6 are known (see “Handbook of Hydraulic Technology”, pages 410 to 420, etc., published by Nikkan Kogyo Shimbun on January 30, 1976).

In FIG. 4, a spool 1, which is a valve element, is housed in a valve body 2 so as to be slidable in the axial direction. The spool 1 is biased by a compression spring 3 on one end side and a plunger 4 on the other end side.
Is in contact with. The plunger 4 generates a thrust force against the biasing force of the compression spring 3 by the electromagnetic force of the solenoid 5 built in the valve body 2, and drives the spool 1. Solenoid 5
Is connected to a control circuit 7 including a microcomputer and a power supply circuit via wirings 6a and 6b, and exerts an electromagnetic force proportional to the magnitude of the control current i corresponding to the applied voltage Vi of the control circuit 7. That is, the plunger 4 and the solenoid 5 constitute a direct-acting type actuator 8 that drives the spool 1 by exerting an electromagnetic force based on the control current i. Further, the valve body 2 is provided with an inlet port 2a, an outlet port 2b and a drain port 2c, and a valve chamber 9 and a bypass passage 9a communicating with these are formed. Then, the actuator 8 is operated by the control current i from the control circuit 7, and the supply hydraulic pressure P _L from a hydraulic power source (not shown) is reduced as necessary by opening and closing the drain port 2c, and the reduced control hydraulic pressure P _C Is supplied to external hydraulic equipment.

On the other hand, the control circuit 7 changes the control current i to control the operation of the actuator 8 and vibrates the control current i as shown in FIG. 5, and the vibration of the control current i causes the spool 1 to move. The actuator 8 is driven with relatively high frequency vibration, that is, dither. The frequency f of this dither is set so as to reduce the frictional force between the spool 1 and the plunger 4 and the valve body 2, and especially the control oil pressure P _C caused by this frictional force.
Is set to a predetermined value so as to reduce the hysteresis in the normal temperature range (shown by the curve H in FIG. 6).

(Problems to be Solved by the Invention) However, in such a conventional electromagnetic proportional control valve control device, the vibration frequency f of the control current i reduces the hysteresis of the control oil pressure P _{C in} the normal temperature range. Since the spool 1 has been set to a predetermined value, when the viscosity of the hydraulic oil becomes high in the low temperature range, the spool 1 cannot fully react to the dither frequency of a relatively high frequency, and the frictional resistance is not reduced. Large hysteresis of the control oil pressure P _C occurred as shown in L). For this reason, the pressure accuracy of the control oil pressure P _C in the low temperature region deteriorates, and the electromagnetic proportional control valve cannot be applied to a hydraulic circuit having a wide operating temperature range.

(Object of the invention) Therefore, according to the present invention, by changing the oscillation frequency of the control current according to the temperature of the hydraulic oil, the dither of the optimum frequency corresponding to the change of the hydraulic oil temperature is applied to the valve body. An object of the present invention is to provide a control device for an electromagnetic proportional control valve suitable for a hydraulic circuit having a wide temperature range.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an electromagnetic proportional control having a valve body that opens and closes a passage for hydraulic oil and an actuator that drives the valve body based on a control current. Connected to the valve,
In a control device for an electromagnetic proportional control valve that applies a control current to an actuator and vibrates the control current to add dither to a valve element, a temperature detection unit that detects the temperature of hydraulic fluid, and a detection unit based on detection information of the temperature detection unit. Variable control means for lowering the dither frequency of the control current as the temperature of the hydraulic oil decreases.

(Operation) In the present invention, the oscillating frequency of the control current is variably controlled by the variable control means based on the detection information of the temperature detecting means. Therefore, the frequency of the dither applied to the valve body is optimally controlled according to the temperature of the hydraulic oil, and normal dithering of the valve body is promoted even when the viscosity of the hydraulic oil increases in a low temperature range. As a result, the frictional resistance of the valve element is reduced in a wide temperature range, and a control device for an electromagnetic proportional control valve suitable for a hydraulic circuit having a wide operating temperature range is provided.

(Example) Hereinafter, one example of the present invention will be described.

1 to 3 are diagrams showing an embodiment of the present invention, which is an example in which the present invention is applied to an electromagnetic proportional pressure reducing valve. The pressure reducing valve in this embodiment is exactly the same as that of the conventional example shown in FIG. 4, and the same reference numerals are used.

First, the configuration will be described. In FIG. 1, reference numeral 11 is an electromagnetic proportional type pressure reducing valve. The pressure reducing valve 11 is connected to a hydraulic pressure source 13 via a supply pressure pipe 12 at an inlet port 2a and a control pressure pipe 14 at an outlet port 2b. Is connected to a load 15 such as a wet multi-plate clutch equipped in the. Further, the control current i of the pressure reducing valve 11 is controlled by the control circuit 16 (described in detail later), and the control current i promotes the operation of the actuator 8 so that the supply hydraulic pressure P _L is reduced to the control hydraulic pressure P _C. (That is, P _L ≧ P _C ).

In FIG. 2, reference numeral 17 denotes a temperature sensor (temperature detecting means) such as a thermistor. The temperature sensor 17 detects the temperature of the hydraulic oil in the pressure reducing valve 11, and the hydraulic oil temperature t _S which is the detected information is supplied to the control circuit 16 Give to. The control circuit 16 is composed of a first control unit 18 and a second control unit 19 (variable control means), and the first control unit 18 responds to signal information N _E , E _T , E _O such as the driving state of the vehicle. The control voltage V _i is output to the second controller 19. The second control unit 19 is provided with a temperature discrimination circuit 21, analog switches 22, 23, current control circuits 24, 25, etc.
Is the input end connected to the temperature sensor 17 and the analog switch
It has two outputs connected to 22 and 23. Also,
The temperature discriminating circuit 21 is composed of a microcomputer, a switch circuit, and the like. The microcomputer of the temperature discriminating circuit 21 has a map of the dither frequency f and the hydraulic oil temperature t _S that minimizes the hysteresis of a predetermined program and control hydraulic pressure P _C. And are remembered. This map is set based on the optimum dither frequency curve A shown in FIG.
The temperature determination circuit 21 indicates that the hydraulic oil temperature t _S has a predetermined value, for example, -5 ° C.
It is determined whether or not it is the above, and one of the output currents i ₁ and i ₂ is output according to the determination result.

That is, when the output current i ₁ is output (when t _S ≧ −5 ° C.), the analog switch 22 is turned on and the analog switch 22 is turned on.
When 23 is turned off and the control voltage Vi from the first controller 18 is applied to the current control circuit 24, the output current i ₂ is output (t _S
At <-5 ° C.), only the analog switch 23 is turned on and the control voltage Vi is applied to the current control circuit 25. Then, when the hydraulic oil temperature t _S is -5 ° C or higher, the current control circuit 24 outputs the control current i proportional to the magnitude of the control voltage Vi to the actuator 8 of the pressure reducing valve 11, and the control current i As shown in FIG. 5, the vibration is performed at the vibration frequency f ₁ , while the current control circuit 25 similarly outputs the control current i when the hydraulic oil temperature t _S is lower than −5 ° C. and it is adapted to vibrate at a lower vibration frequency f ₁ oscillation frequency f ₂ (see FIG. 3). When the current control circuits 24 and 25 vibrate the control current i, the amplitude is kept constant.

Next, the operation will be described.

When the vehicle is started, signal information is sent to the first control unit 18 of the control circuit 16.
When N _E , N _T , N _O, etc. are given, the control voltage Vi corresponding to the signal information N _E , N _T , N _O is output from the first control unit 18 to the second control unit 19, and the temperature determination circuit 21 The following processing is executed every predetermined time.

First, it is determined whether or not the hydraulic oil temperature t _S, which is the detection information of the temperature sensor 17, is a predetermined value, for example, −5 ° C. or higher. Then, from this determination result, when the hydraulic oil temperature t _S is higher than the predetermined value, The control current i ₁ is output to the analog switch 22, or the control current i ₂ is output to the analog switch 23 when the hydraulic oil temperature t _S is lower than a predetermined value. Therefore, if the hydraulic oil temperature t _S is higher than the specified value, the analog switch 22 turns ON.
Then, the control voltage Vi is applied to the current control circuit 24, and the control current i from the current control circuit 24 to the pressure reducing valve 11 with the vibration frequency f ₁ is generated.
Is output. At this time, since the viscosity of the hydraulic oil is relatively low, dithering of the spool 1 is easily promoted when a thrust force corresponding to the vibration frequency f ₁ of the control current i is applied by the actuator 8 of the pressure reducing valve 11.

On the other hand, when the hydraulic oil temperature t _S is lower than the predetermined value, the analog switch 23 is turned on, the control voltage Vi is applied to the current control circuit 25, and the current control circuit 25 causes the pressure reducing valve 11 to control the control current with the vibration frequency f _2. i is output. At this time, although the viscosity of the hydraulic oil is relatively high, the actuator 8 of the pressure reducing valve 11
With a vibration frequency f ₂ lower than the vibration frequency f ₁
Since the spool 1 is driven by, when the thrust force based on the control current i is applied to the spool 1, the spool 1 exhibits a reaction corresponding to the vibration frequency f ₂ . That is, dithering of the spool 1 is easily promoted.

As described above, according to the present embodiment, the oscillation frequency of the control current i is reduced by the second control unit 19 as the temperature of the hydraulic oil decreases based on the detection information of the temperature sensor 17, and the pressure reducing valve 11
Since the frequency of the dither applied to the spool 1 is optimally controlled according to the operating oil temperature, the dither of the pressure reducing valve 11, which is the valve body, is easily promoted even in the low temperature range. Therefore, the frictional resistance of the valve element is reduced in a wide temperature range, the hysteresis of the control oil pressure P _C is reduced, and the pressure accuracy of the control oil pressure P _C is improved. As a result, a device suitable for a hydraulic circuit having a wide operating temperature range such as an operating hydraulic circuit such as a wet clutch mounted on a vehicle is provided.

In the present embodiment, the electromagnetic proportional control valve is a pressure reducing valve, but the present invention is not limited to this and can be applied to an electromagnetic proportional pressure control valve, flow rate control valve, and the like.

(Effect) According to the present invention, the variable control means lowers the dither frequency of the control current as the temperature of the hydraulic oil decreases based on the detection information of the temperature detecting means, and applies the dither applied to the valve body to the temperature of the hydraulic oil. Since the optimum frequency is controlled according to the above, even if the viscosity of the hydraulic oil becomes high in the low temperature range, normal dithering of the valve body can be promoted, and the frictional resistance of the valve body can be reduced over a wide temperature range. As a result, the hysteresis can be reduced and the accuracy of the control valve can be improved. As a result, it is possible to provide a control device for an electromagnetic proportional control valve suitable for hydraulic equipment having a wide operating temperature range.

[Brief description of drawings]

1 to 3 are views showing an embodiment of a control device for an electromagnetic proportional control valve according to the present invention, and FIG. 1 is an overall configuration diagram thereof,
FIG. 2 is a circuit diagram of its main part, and FIG. 3 is a graph showing the relationship between the dither frequency and the hydraulic oil temperature. 4 to 6 are views showing a conventional example, FIG. 4 is a sectional view of the electromagnetic proportional control valve, FIG. 5 is a graph showing the waveform of the control current, and FIG. 6 is the outlet of the control valve. It is a graph which shows the relationship between oil pressure and control current. 1 ... Spool (valve body), 8 ... Actuator, 11 ... Pressure reducing valve (electromagnetic proportional control valve), 17 ... Temperature sensor (temperature detection means), 19 ... Second control unit (variable control means) , F ₁ , f ₂ ... vibration frequency, i ... control current, t _S ... hydraulic oil temperature (detection information).

Claims (1)

[Claims] 1. An electromagnetic proportional control valve having a valve body for opening and closing a passage for hydraulic oil and an actuator for driving the valve body based on the control current, the control current being applied to the actuator and the control current being oscillated. In the control device for the electromagnetic proportional control valve that adds dither to the valve element, the temperature detection means for detecting the temperature of the hydraulic oil, and the control current of the control current increases as the temperature of the hydraulic oil decreases based on the detection information of the temperature detection means. A control device for an electromagnetic proportional control valve, comprising: variable control means for lowering the dither frequency.