JPH02261987A - Proportional solenoid valve drive output correcting device - Google Patents

Abstract

PURPOSE:To make the oil pressure constant by allowing a CPU to sense the current value flowing through a proportional solenoid valve fitted on the transmission of an agricultural working vehicle, comparing the output therefrom with a reference value specified for the solenoid valve, and correcting the output On time due to pulse width modulation either to Long or Short. CONSTITUTION:By a transistor circuit 2 in connection with a CPU 3, the output current flowing through a solenoid 22 is supplied restrictedly with the output On time in the output periods due to pulse width modulation to be controlled by interrupt processing of the CPU 3. Immediately before each output time goes out, the output current value is sensed by a calculational amplifier 23 and sent to the CPU 3. The CPU 3 compares it with a reference current value for the pre-registered output On time. According to the result therefrom an output On time correcting circuit A makes correction so that the output On time becomes shorter when the lubricant temp. in the transmission concerned 6 at starting of the work is low and when the current value flowing through the solenoid 22 is large. This enables maintaining the oil pressure constant at all times regardless of the current value flowing through the solenoid 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a proportional solenoid valve drive output correction device, and can be used in a drive circuit for driving a proportional solenoid valve.

Problems to be Solved by the Prior Art and the Invention In a hydraulic system operated by hydraulic pressure, a proportional solenoid valve used to operate a hydraulic actuator is used to raise and lower a working device such as an agricultural vehicle from the ground. If so, operate this proportional solenoid valve! The proportional solenoid valve is controlled by the current flowing through the magnetic coil during the output ON time of pulse width modulation by a transistor circuit connected to the CPU. The value of the current flowing through the CP
Read with U 1 Due to various factors, for example, when the proportional solenoid valve is installed in the transmission of an agricultural vehicle, etc., the temperature of the solenoid coil may rise as the temperature of the lubricating oil rises due to the operation of the transmift 1. This temperature rise increases the internal resistance of the electromagnetic coil, and the transistor circuit reduces the output current flowing to the electromagnetic coil during the output ON time. This decrease in the output current causes the hydraulic pressure generated by the proportional solenoid valve to decrease, resulting in a problem in that the lifting speed of the worker M in the agricultural vehicle or the like becomes slow, thereby impairing the work efficiency.

Therefore, in the present invention, the current value flowing through the proportional solenoid valve is detected by the CPU, this detected value is compared with a specified current value of the proportional solenoid valve, and based on the result, the output ON time is increased by pulse width modulation.・This is intended to be a short correction.

Means for Solving the Problems This invention provides a transistor circuit (2) that drives a proportional solenoid valve (1), and a transistor circuit (2) that flows through the transistor circuit (2).
In a drive circuit having a CPU (3) for detecting the magnitude of the current, the CPU (3) detects the magnitude of the current immediately before the end of the ON time of each pulse.

A proportional solenoid valve drive output correction device is provided with an output ON time correction circuit (A) that corrects the output ON time of pulse width modulation to lengthen or shorten it by comparing the detected current value and a preset specified current value. composition.

Functions and Effects of the Invention According to the above configuration, the transistor circuit (2) drives the electromagnetic coil that opens and closes the valve of the pressure oil port of the proportional electromagnetic valve fjl.
The electromagnetic coil of the proportional solenoid valve (1), which outputs hydraulic pressure by controlling the flow rate of pressure oil in the hydraulic circuit in proportion to the amount of current flowing through the CPU (
3), and this CP TJ (3) causes an output current to flow according to the output cycle and output ON time by pulse width modulation, and the magnitude of the output current just before the end of this output ON time is detected by the CPU T3). For example, in the case where the proportional solenoid valve fil is installed in the transmission of an agricultural vehicle, the detected current value may change due to some factors. As the temperature of the electromagnetic coil rises and its internal resistance increases, the detected current value is
When the current value is on the decreasing side compared to the specified current value registered in U (3), the CPU
Output ON time correction circuit (A) mainly configured with (3)
By performing the correction, the proportional solenoid valve (1) always regulates the flow rate of the hydraulic oil and maintains the hydraulic pressure constant, regardless of the magnitude of the current flowing through the electromagnetic coil. . Further, when this detected current value is on the increasing side compared to the specified current value, the correction opposite to the above may be performed.

As described above, by correcting the hydraulic pressure of the proportional solenoid valve (1) to be constant, for example, when a working device such as an agricultural vehicle is raised or lowered by the proportional solenoid valve (1), the lifting speed can be adjusted. These corrections will not affect the work efficiency due to changes in the CPU.
(3) is carried out by the output ON time correction circuit (A), which is mainly arranged, so the circuit configuration is not only simple, but also
Correction is performed by detecting the output current immediately before the end of the output ON time for each output cycle of pulse width modulation, so unlike correction based on the average value of the output current that is normally performed, the correction is performed based on changes in the output current value. It has extremely good responsiveness and is particularly effective in agricultural vehicles and the like, where the magnitude of output often changes.

Embodiment In the rotation, a case where the present invention is applied to a tractor as an example of an agricultural vehicle etc. will be exemplified.

The tractor body (4) is long from front to back, and an engine (5) is mounted at the front of the tractor, and from the engine (5) toward the rear there is a transmission (6) with a gear change linking end installed inside.
are connected via a clutch device, and from this transmission (6) are left and right front axles (7) located on the front side of the vehicle body (4), and left and right rear axles (8) located on the rear side.
The configuration is such that power can be transmitted to each of the two.

Further, a bonnet (9) is provided to cover the engine (5),
A control device 1)0 for controlling the tractor rearward from the rear end of this bonnet (9) and a pilot seat 01) for this control are provided, and a handle o of the control device +IIn is provided.
The front wheels (7) are connected and configured to be steerable by X5.

In addition, a working transmission system for branching and transmitting power to the rear PTO shaft (13) is arranged independently of the driving transmission system in the transmission (6), and is directed rearward from the rear end position of the transmission (6). It was extended.

A three-point linkage machine U consisting of a top link 04) at the upper position and a pair of left and right lower links (19) at the lower position.
In (B), a rotary tiller (10 is connected and attached to the rear of the vehicle body (4) and the transmission f6), which is an example of one working device, has a loosely fitted shaft shown on the upper surface of the rear of the vehicle. With lift arm (1'7).

The pair of left and right lower links (one and each connecting rod (
Concatenate by old. Also, the transmission (6)
A proportional solenoid valve (1) installed on the - side to control the pressure oil of the hydraulic circuit is connected to 1c1 by a hydraulic actuator for hydraulic control, and this hydraulic actuator (one) is connected to the lift arm (r71). , by vertically moving the lift arm ((7)), the rotary tilling device ff! The rotary claws +2CI are rotated and connected to each other so that tillage can be driven.

In addition, the cockpit (control box + 21 on one side of 1υ)
CPU (3) is placed in this control box I21).
) is provided internally with an output ON time correction circuit (A) mainly arranged. This output ON time correction circuit (A) is a solenoid coil Qa that opens and closes the pressure oil port of the proportional solenoid valve (1).
is electrically connected to one end of a transistor circuit (2) that causes an operating current to flow through the mat coil αδ, and the other end of this transistor circuit (2) is electrically connected to the CPU (3), and the transistor An operational amplifier □ that detects the current value flowing from circuit (2) in parallel to the electromagnetic coil Qδ
Connect one end of □□ and connect the other end to A/
It is configured by being electrically connected to the CPU (3) via the D converter (a).

In the tractor configured as described above, when working with the rotary tilling device (1e) attached to the vehicle body (4) of the tractor, the rotary tilling device [flFA] is frequently used during one work by using the three-point linkage mechanism (B). The lift arm (m) is a proportional solenoid valve [1] arranged in the hydraulic circuit.
The vertical movement speed is increased or decreased depending on the flow rate of the pressure oil, and the flow rate of the pressure oil at this time is determined by the electromagnetic coil Q that opens and closes the pressure oil port of the proportional solenoid valve (1).
It is controlled by the amount of operating current flowing through 3.

The output current flowing through this electromagnetic coil is CPU (3)
A transistor circuit (21) connected to the CPU
The output current value is regulated by the output ON time in the output cycle by pulse width modulation managed by the interrupt processing in (3), and the output current value is detected by the operational amplifier port immediately before the end of each output ON time, and the output current value is detected by the operational amplifier port. U (3
), the CPU compares the specified current value and the detected current value for the pre-registered pressure ON time, and based on this comparison result, the output ON time correction circuit (A) When the temperature of the lubricating oil in the transmission (6) is low at the start of the operation and the current value flowing through the electromagnetic coil (2i5) is large, the output ON time is corrected to be shortened, and as the work progresses, the transmission (6) As the temperature of the lubricating oil increases, the electromagnetic coil C3
When the internal resistance increases and the flowing current value decreases, the output ON time is corrected to be longer.

By correcting the output ON time, the proportional solenoid valve (
Since it is possible to control the pressure oil flow rate from the first point and maintain the hydraulic pressure constant, the rotary tilling device 1!
(The work efficiency will not be hindered due to a change in the lifting speed of Ile, and these corrections can be made in accordance with the above-mentioned CP TJ.
(3) is carried out by the output ON time correction circuit (A), which is mainly arranged, so the circuit configuration is not only simple, but also
Since the correction is performed by detecting the output current immediately before the end of the output ON time for each pulse width modulation output cycle, unlike the normal correction based on the average value of the output current, it is difficult to compensate for changes in the output current value. This is particularly effective for tractors that have extremely good responsiveness and often change the amount of output.

[Brief explanation of drawings]

The figures show an embodiment of the invention, and Figure 1 is a side view;
2 and 3 are waveform diagrams, FIG. 4 is an electric circuit block diagram, and FIG. 5 is a flow chart. In the figure, reference numeral (1) indicates a proportional solenoid valve, (2) a transistor circuit, and (3) a CPU.

Claims (1)

[Claims] Transistor circuit (2) that drives the proportional solenoid valve (1)
and a CPU (3) that detects the magnitude of the current flowing through the transistor circuit (2),
This CPU (3) detects the magnitude of the current just before the end of the ON time of each pulse, and compares this detected current value with a preset specified current value to increase the output ON time of pulse width modulation. Output ON time correction circuit (A
) A proportional solenoid valve drive output correction device.