JPS5855647B2 - temperature compensated solenoid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a proportional control solenoid, and more particularly to a solenoid that compensates for a decrease in magnetomotive force caused by an increase in the temperature of an excitation winding.

Conventionally, the proportional layer IJ solenoid was a joystick (
It is often used in conjunction with a variable resistor (a type of variable resistor) in continuous energization in construction machinery, etc., and the temperature rise in the excitation winding due to energization becomes so large that it cannot be ignored, resulting in an increase in the winding resistance. If a constant voltage power source such as a battery is used, the drive current will eventually decrease, and the electromotive force will become smaller. For example, when controlling a hydraulic valve using a solenoid force, the output fluid will be reduced, which has a significant effect.

Therefore, the present invention aims to provide a novel solenoid in which a resistance element having a negative temperature coefficient is connected in series to the excitation winding in order to compensate for the decrease in magnetomotive force due to temperature rise.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a two-way solenoid according to the present invention, and numerals 1 and 2 are fixed iron cores installed on the left and right sides, respectively, and these fixed iron cores 1 and 2 are fitted with a cylindrical yoke 3.

4 and 4A are bearings that support the movable iron core 6 so as to be slidable in the axial direction, and non-magnetic bushings 5 and 5A are installed between the bearings 4 and 4A and the fixed irons 1 and 2, respectively. This magnetically isolates the bearings 4, 4A.

7.7A is a non-magnetic spacer that prevents the movable core 6 from adhering to the fixed cores 1 and 2.

Coil winding frames 8, 8A are arranged in the space formed by the central inner protrusion 3A of the yoke 3 and the stators 1, 2, and excitation windings 9, 9A are wound around these, respectively. .

10 and 1 OA are excitation windings connected so that the winding directions are the same and parallel to the excitation windings 9 and 9A, respectively, and the excitation windings 9 and 10 (or 9
The structure is such that the sum of the magnetomotive forces caused by A and 1 OA) becomes the solenoid output.

The excitation windings 9, 10, 9A, and 10A are energized separately, and the movable iron core 6 moves leftward and rightward to the spring 1.
2, 12A to a predetermined balance position.

11.11A are thermistors, each with excitation winding 1
Connected in series to 0.1OA.

Figure 2 shows the connection between the excitation windings 9 and 10 on the left side of Figure 1 and the thermistor 11, and R1 and R2 are the excitation windings 9 and 10.
shows the resistance value.

R3 indicates the resistance value of the thermistor 11.

VR is part of the joystick variable resistor and excitation winding 9
This is a setting section for setting the 0 current to 0.

FIG. 3 shows a conventional solenoid connection circuit, and R4 indicates the resistance value of the excitation winding.

FIG. 4 shows the change in characteristics of a conventional solenoid without temperature compensation (broken line) and the change in characteristics of the temperature-compensated solenoid according to the present invention (solid line) when the temperature rises.

To explain this figure, in the conventional solenoid, as the temperature increases from, for example, 10 to tl and t2, the resistance R4 increases, and the constant voltage power supply (2) causes the current (2) to decrease.

As a result, the magnetomotive force (NI: number of turns x current) also decreases,
The output performance of the solenoid decreases.

When designing the magnetomotive force, the design calculation is performed at a temperature in the middle of the allowable temperature range, so in this example, the magnetomotive force at the temperature t1 is the rated value.

If the line of the rated magnetomotive force is represented by the symbol ■, it will be less than ■ in the temperature range from t1 to t2, the solenoid output will be insufficient for the rated value, and the maximum output will decrease, for example, the speed of hoisting and hoisting of cranes etc. However, this will also lead to deterioration in operational performance.

However, according to the temperature compensation method according to the present invention, the drop in magnetomotive force is greatly improved as shown by the solid line.

Next, let's analyze the change in resistance due to temperature rise in Figure 3.

In the following example, the resistance of the variable resistor will be omitted.

The total resistance R in Figure 3 is (assumed to be R1, R2°R3 at a temperature of 7°C).The increase in resistance value due to temperature rise is 1JR1, JR2°JR3.
Then, each resistance value R1', R2' at t2.

R3' is the sum of the resistance R2 of the excitation winding 10 and the resistance R3 of the thermistor 11, which becomes R2<R3'<R2+R3 due to the temperature rise.

Utilizing this tendency, an attempt is made to compensate for the decrease in magnetomotive force due to a decrease in current value (1) due to a rise in temperature of resistor R1 of excitation winding 9 by increasing current I2 flowing to excitation winding 10.

The reason for configuring the parallel circuit in this way is that the current carrying capacity of the thermistor is relatively small, so the method of connecting the thermistor in series with the excitation winding shown in Figure 3 cannot secure the current value necessary for the magnetomotive force. be.

In addition, the combined resistance value including the excitation winding and thermistor is held constant even if there is a temperature change, and the command current value 1-11 + I2 corresponds 1:1 to the value of the variable resistor VR, which serves as an external command means for magnetomotive force. This is because it is necessary.

Showing numerical values as one example: Next to it, the resistance R1 current ■ is constant.

As explained above, in the present invention, the excitation winding of a solenoid is divided into two parts, a thermistor is connected in series to one of the winding parts to form a compensation circuit, and the other winding part is connected to the two parts. By appropriately selecting the resistance values of these partial windings connected in parallel and the resistance-temperature characteristics of the thermistor, it has become possible to form a solenoid with little change in magnetomotive force even when temperature changes.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the essential parts of the two-way solenoid according to the present invention, Fig. 2 is a circuit connection diagram of the left side solenoid in Fig. 1, Fig. 3 is a circuit connection diagram of a conventional solenoid, and Fig. 4 is It is a graph showing changes in magnetomotive force, current, and resistance value with respect to temperature changes. 1.2... Fixed iron core, 3... Connector, 4
...Bearing, 5...Button, 6...
...Movable iron core, 7...Spacer, 8...
... Winding frame, 9, 10... Excitation winding, 11...
...Thermistor.

Claims (1)

[Claims] 1. In a solenoid that controls magnetomotive force by changing the current flowing to an excitation winding connected to a constant voltage DC power supply, the excitation winding is connected to a first. It is divided into a second winding part, and a compensation circuit configured by a series connection of the second winding and a resistance element having a negative temperature coefficient is connected in parallel to the first winding. A temperature compensated solenoid featuring: