JPH0451702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for a solenoid valve that switches and controls hydraulic actuators such as hydraulic cylinders and hydraulic motors.

2. Description of the Related Art Conventionally, in loading devices for garbage collection vehicles, hydraulic actuators such as hydraulic cylinders and hydraulic motors have been used, and the hydraulic actuators are controlled by electromagnetic valves.

When the temperature of the oil flowing through the hydraulic control circuit of the hydraulic actuator changes, its viscosity also changes.
For this reason, the response of the solenoid valve is also inconsistent. That is, the responsiveness of the solenoid valve depends on the switching speed of the spool, and this switching speed is greatly influenced by the viscosity of the oil, and when the temperature of the oil is low, the viscosity increases, and therefore the operation of the spool is affected. Resistance increases and switching speed becomes slower. Conversely, when the temperature of the oil is high, the viscosity decreases, which reduces the operating resistance of the spool and increases the switching speed. When the spool switching speed is slow, the flow rate of oil passing through the solenoid valve is higher than the predetermined value, and conversely, when the spool switching speed is fast, the flow rate of oil passing through the solenoid valve is lower than the predetermined value. This causes a problem in that the amount of movement of the hydraulic actuator, for example, the amount of movement of the piston rod in a hydraulic cylinder, is not constant.

The present invention has been made in view of such conventional problems, and utilizes the characteristics of a surge killer circuit provided to remove surge voltage from a solenoid to change the switching time of a solenoid valve according to the oil temperature. It is an object of the present invention to provide a control circuit for a solenoid valve that selects and controls the solenoid valve so that its responsiveness does not change depending on the oil temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the drawings.

A garbage collection vehicle equipped with a control circuit according to the present invention is shown in FIG. It is a garbage processing frame that is pivotally connected to be able to open and close upward via a pin 11, and the garbage processing frame 3
A garbage pushing device 4 is installed inside. The garbage pushing device 4 is composed of a hydraulic cylinder 5, a pushing plate 6, a rotary plate 7, etc. In the hydraulic cylinder 5, the tip 8a of a piston rod 8 is pivoted to an extension arm 9 of the pushing plate 6, and the base end 5a is pivoted to an extension arm 9 of the pushing plate 6. It is pivotally attached to a pedestal 10 that projects above the open upper part 2a of the garbage storage box 2. The hydraulic cylinder 5 acts to swing the push plate 6 and to open and close the processing frame 3. In addition, 1
A stopper 2 is fixed to the processing frame 3 and engages with the extension arm 9 of the push plate 6 to transmit the operating force of the hydraulic cylinder 5 to the processing frame 3.

Further, the hydraulic control circuit 13 of the hydraulic cylinder 5
As shown in Fig. 2, the 4-port 3-position switching valve 1
4, and the switching valve 14 is a solenoid valve of a solenoid valve control type having solenoids SOLa and SOLb for operating the valve spool. Note that 15 is a hydraulic pump, 16 is an oil tank, and 17 is a filter.

Next, an embodiment of the control circuit 18 of the solenoid valve 14 according to the present invention is shown in FIG. 3, in which 19 is a diode, 20 is a ceramic varistor, 21 is a capacitor, and 22 is a relay. 4
As shown in the figure, it is connected in series to the temperature sensor 23. The diode 19 is connected in parallel with the solenoid SOL (SOLa, SOLb) of the solenoid valve 14,
Constructs a surge killer circuit with slow valve response. Further, the ceramic varistor 20 and the capacitor 21 are connected in parallel, and this parallel circuit is connected in parallel with the solenoid SOL to form a surge killer circuit having quick valve response.

The relay 22 has an a contact connected in series to a diode 19, and a b contact connected in series to a parallel circuit of a ceramic varistor 20 and a capacitor 21, and these switching operations are performed by a temperature sensor 23.
This is done by

The temperature sensor 23 is provided in the above-mentioned hydraulic control circuit 13 and opens and closes in response to the temperature of the oil flowing through the hydraulic control circuit 13. That is, when the oil pressure temperature is lower than the set value, the temperature sensor 23
is in the OFF (open) state, so relay 2
2 is not excited, the b contact is closed as shown in FIG. 3, and current flows through the parallel circuit of the ceramic varistor 20, which has a fast valve response, and the capacitor 21.
On the other hand, if the oil temperature rises above the above set value,
The temperature sensor 23 is turned on (closed), energizing the relay 22, and conversely to the above, the a contact closes, and the current flows to the diode 19, which has a slow valve response. The above set value is set in consideration of the relationship between the viscosity of the oil and the switching speed of the spool of the solenoid valve 14, and the relationship between the valve responses of both the surge killer circuits.

Then, the control circuit 18 switches the position of the solenoid valve 14 to control the direction in which the oil flows, thereby causing the piston rod 8 of the hydraulic cylinder 5 to move in and out, thereby operating the garbage pushing device 4. The frame 3 is opened and closed. At this time, when the temperature of the oil in the hydraulic control circuit 13 is low, the viscosity is high, and the switching speed of the spool of the solenoid valve 14 is slow, the b contact side is closed, so a surge suppressor circuit (ceramic varistor) with quick valve response 20 and capacitor 21) work to compensate for this slowness. Conversely, when the temperature of the oil is high, the viscosity is low, and the switching speed of the spool of the solenoid valve 14 is fast, the a contact side is closed and the valve is closed. A surge killer circuit (diode 19) with slow response works. Therefore, the responsiveness of the solenoid valve 14 is made not to change depending on the oil temperature, and the flow rate of the oil flowing through the solenoid valve 14 is maintained at a predetermined value, so that the position control of the piston rod 8 of the hydraulic cylinder 5 is stabilized. It is done as follows.

In addition, instead of the parallel circuit of the ceramic varistor 20 and the capacitor 21, a series circuit of a capacitor and a resistor, a ceramic varistor, a Zener diode, or a parallel circuit of a Zener diode and a capacitor may be used as a quick response surge killer circuit. good.

In addition to the hydraulic cylinder 5 of the garbage pushing device 4, the control circuit 18 also includes a hydraulic motor (not shown) for the rotary plate 7, and a hydraulic cylinder 2 for dumping the garbage storage box 2.
4, or a locking valve 25 that locks the garbage processing frame 3
It can also be applied to solenoid valves that switch and control hydraulic actuators such as the hydraulic cylinder 26 (see Fig. 1) for use in a motor vehicle. You may also do so.

Furthermore, in the above-mentioned embodiment, the surge killer circuit is switched in two stages, but this is not limited to this. The responsiveness of the solenoid valve 14 can be made constant. For example, using an integral circuit, input a signal corresponding to the oil temperature into the integral circuit, and adjust the conduction time of the solenoid SOL of the solenoid valve 14 steplessly and continuously according to the signal output from the integral circuit. Let it change.

As described above, according to the present invention, by utilizing the characteristics of the surge killer circuit provided to remove the surge voltage of the solenoid, a surge absorption section with slow valve response and a surge absorption section with quick valve response are combined. The viscosity of the oil flowing in the hydraulic control circuit of the hydraulic actuator changes by connecting each solenoid in parallel with the solenoid of the solenoid valve and switching the relay's a contact and b contact based on the temperature detected by the oil temperature detector. Even when the electromagnetic valve is operated, the responsiveness of the electromagnetic valve can be controlled to be substantially constant, the flow rate of oil passing through the electromagnetic valve can be maintained at a predetermined value, and the operating speed of the hydraulic actuator can be controlled to be substantially constant with high precision.

This is particularly effective for devices that maintain operation at a constant speed from the standpoint of safety.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing the rear part of a garbage collection vehicle, and FIG. 2 is a schematic diagram showing a hydraulic control circuit of a hydraulic cylinder of a garbage pushing device provided at the rear part of the vehicle. 3 is a diagram showing a main part of a control circuit for a solenoid valve in the same hydraulic control circuit, and FIG. 4 is a diagram showing a connection circuit between a relay and a temperature sensor in the same control circuit. 5... Hydraulic cylinder, 13... Hydraulic control circuit, 14
...4 port 3 position switching valve, 18...control circuit, 19
...Diode, 20...Ceramic varistor, 21
...Capacitor, 22...Relay, 23...Temperature sensor, 24, 26...Hydraulic cylinder.

Claims (1)

[Scope of Claims] 1. In a hydraulic control circuit that switches and controls a hydraulic actuator using a solenoid valve, an electric circuit that controls switching of the solenoid valve is connected to the solenoid of the solenoid valve, and this electric circuit is connected to the solenoid of the solenoid valve. A surge absorbing section with a slow valve response and a surge absorbing section with a fast valve response are connected in parallel to the solenoid, respectively, an a contact is connected in series to the surge absorbing section with a slow valve response, and a b contact is connected in series to the surge absorbing section with a slow valve response. and a relay connected in series to the surge absorption section with quick valve response.Furthermore, the hydraulic control circuit is provided with an oil temperature detector for detecting the temperature of oil flowing through the hydraulic control circuit. The relay is characterized in that the B contact of the relay is closed when the detected temperature detected by the temperature detector is lower than the set value, and the A contact of the relay is closed when the detected temperature is higher than the set value. control circuit for a solenoid valve. 2. The control circuit for a solenoid valve according to claim 1, wherein the surge absorber having slow valve response is a diode. 3. The control circuit for a solenoid valve according to claim 1, wherein the surge absorbing section with quick valve response is a parallel circuit of a varistor and a capacitor.