JPH09137878A - Freezing preventing device for solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of detective operation due to freezing of a solenoid valve to control a fluid pressure by a method wherein during a time in which no drive current is fed to a solenoid valve, a pulse current is fed to a drive winding in a duty ratio below the working limit of the solenoid valve. SOLUTION: When an atmosphere temperature is decreased to a value lower than a given value, a working switch 9 is automatically closed, a power source is fed to a source input terminal 8 from a source battery 7 and simultaneously, a display lamp 10 lights and displays that a pulse current generator 4 is in an operation state. Meanwhile, an output from a drive circuit 1 is fed to the control input terminal 5 of the pulse current generator 4 and a solenoid valve drive current is fed to the drive winding 3 of a solenoid valve 2. Further, the pulse current generator 4 feeds a pulse current in a duty ratio, being below the working limit of the solenoid valve 2, to the drive winding 3 during a time in which no drive current is fed to the drive winding 3 of the solenoid valve 2 from a drive circuit 1. This constitution performs heating by a low consumption power and prevents freezing of the solenoid valve 2 during low temperature operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can be widely used in a device for controlling the pressure of gas or liquid by means of a solenoid valve. INDUSTRIAL APPLICABILITY The present invention is particularly suitable for use in a drive circuit of a solenoid valve mounted on an automobile. The present invention relates to an electric circuit for preventing a solenoid valve from freezing in winter and causing malfunction.

[0002]

2. Description of the Related Art A computer control device has been used in a brake system of an automobile, and the main valve provided in a passage for introducing the air pressure of the brake device into a brake cylinder is constituted by an electromagnetic valve. did.
In particular, ABS (anti-lock brake system) has been installed in large vehicles, and high-performance and inexpensive parts have been developed for both the solenoid valve and the brake cylinder.

[0003] The mounting position of such a solenoid valve is taken into consideration so that it does not freeze due to running in a cold zone in winter.
The device is provided with a heating means, and is devised such that an alarm is issued before malfunction occurs even if the scale freezes, and the operation is performed on the safe side even if the freeze operation malfunctions.

As a conventional example for this purpose, there is a technique disclosed in a prior application (Japanese Patent Laid-Open No. 6-74361) filed by the present applicant. This is to prevent freezing at low temperature by supplying the solenoid valve winding, which has the possibility of freezing, with a current of the opposite polarity to the operating current to heat the winding when drive current is not supplied to that winding. To do. This device is an excellent device and has an excellent anti-freezing effect, but it requires multiple relay contacts in the circuit for supplying current of opposite polarity, which makes the device expensive and makes a lot of noise. However, the large power consumption to prevent freezing, and the one that generates a reverse voltage by dividing the power supply voltage into two are suitable for large vehicles equipped with a 24V battery because it is easy for the battery to slip. It had some drawbacks, such as being difficult to fit in.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and it is not necessary to equip a special heating device, and it is possible to prevent the solenoid valve from freezing with a simple structure. It is an object of the present invention to provide an electric circuit that can be used. It is an object of the present invention to provide an antifreezing device that can eliminate the possibility of contact freezing and the operating noise of contacts by eliminating electrical contacts. An object of the present invention is to provide an antifreezing device that can be realized by a relatively inexpensive semiconductor switch. An object of the present invention is to provide a device that can reduce the power consumption for freeze prevention. An object of the present invention is to provide an antifreezing device suitable for a large vehicle having a 24V power supply system.
It is an object of the present invention to provide a device that does not have a one-sided battery.

[0006]

The present invention is characterized in that it is provided with means for preventing malfunction due to freezing of a solenoid valve for controlling the pressure of gas or liquid.

That is, the present invention provides a pulse current generator for supplying a pulse current to the drive winding at a duty ratio below the operating limit of the solenoid valve during the time when the drive current is not supplied from the drive circuit to the drive winding of the solenoid valve. It is characterized by having.

Various devices operated by atmospheric pressure or hydraulic pressure are controlled by electromagnetic valves that open and close by supplying or stopping a drive current from a drive circuit. When the drive current is supplied to the drive winding of this solenoid valve, it is heated by heat generation, but it is not heated when the drive winding is not supplied with current, and the vehicle runs in a low temperature zone in winter. It may freeze.

As described above, when the drive current is not supplied to the drive winding and the ambient temperature is lower than the predetermined temperature, the pulse current having a small duty ratio is automatically supplied to the drive winding. The duty ratio is set so that the solenoid valve does not operate due to this pulse current, and power consumption is minimized. By supplying a current to the drive winding as a pulse current at a duty ratio equal to or less than the operation limit of the solenoid valve, it is possible to heat with a small power consumption and prevent the solenoid valve from freezing at low temperatures.

Since the output voltage of the drive circuit can be connected to the pulse current generator by providing the control input terminal, the pulse current generator can be connected to the pulse current over the period in which the output voltage is supplied to the drive winding. The output can be stopped automatically.

Further, a first reverse current preventing diode (D ₁ ) in the forward direction is connected to the path for supplying the driving current to the driving winding, and a second diode in the forward direction is connected to the output voltage of the driving circuit. By connecting the backflow prevention diode (D ₂ ) in advance, backflow of current to the drive circuit side is prevented, and effective current supply to the drive winding can be performed.

The inhibiting means of the pulse current generator is activated immediately when a voltage is supplied to the control input terminal, that is, when the solenoid valve is operated, and the pulse current generator supplies a voltage to the drive winding. Can be stopped, and when the voltage supplied to the control input terminal is reduced (when the voltage is not supplied to the drive winding), the operation can be released after the elapse of a predetermined delay time t. . By providing the delay time t, since the pulse current is supplied after the operation of the solenoid valve is stopped and the plunger is surely returned, it is possible to avoid a malfunction in which the solenoid valve cannot be fully returned. .

The pulse current generator can be continuously operated even when the drive current is being supplied from the drive circuit. In this case, the pulse current generator supplies the output pulse current to the drive winding. The third forward-flow preventing diode D ₃ in the forward direction is connected to the current. This structure simplifies the structure of the pulse current generator.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing the overall construction of the first embodiment of the present invention, and FIG. 2 is a block diagram showing the construction of a pulse current generator in the first embodiment of the present invention.

In the first embodiment of the present invention, the driving circuit 1 for driving various atmospheric pressure or hydraulic devices, for example, an ABS (Antilock Brake System) device, is driven at a time when the driving current is not supplied to the driving winding 3 of the solenoid valve 2. The winding 3 is provided with a pulse current generator 4 for supplying a pulse current with a duty ratio equal to or less than the operation limit of the solenoid valve 2. The pulse current generator 4 is provided with a control input terminal 5, and the control input terminal 5
An output voltage of the drive circuit 1 is connected to the output terminal of the drive circuit 1, and a prohibition unit that stops the pulse current output for a period during which the output voltage is supplied is included.

Further, a first reverse current preventing diode D ₁ in the forward direction is connected to the path for supplying the drive current to the drive winding 3, and a second reverse current in the forward direction is applied to the output voltage of the drive circuit 1. The protection diode D ₂ is connected. The prohibiting means is activated immediately when a voltage is supplied to the control input terminal 5, and is deactivated after a delay time t after the voltage of the control input terminal 5 disappears. The pulse current generator 4 is configured to continuously operate even while the drive current is being supplied,
A third backflow preventing diode D ₃ in the forward direction is connected to the pulse current at the output terminal 6 of the passage for supplying the output pulse current to the drive winding 3.

An operation switch 9 is provided between the power supply battery 7 and the power supply input terminal 8 of the pulse current generator 4. The operation switch 9 is an operation switch that drives the pulse current generator 4. Further, the temperature switch can be automatically closed when the temperature becomes lower than a predetermined temperature. An indicator lamp 10 is provided to indicate that the drive circuit 1 is operating when the operation switch 9 is closed. This indicator light is placed in the driver's seat.

FIG. 2 shows a configuration example of the pulse generator 4. In this example, an oscillator 11 and this oscillator 1 are used.
1, a semiconductor switch circuit 12 that opens and closes according to a control input from a control input terminal 5, a duty ratio adjusting circuit 13 that is connected to the semiconductor switch circuit 12 and adjusts a duty ratio, and a duty ratio adjusting circuit 1
The variable resistor 14 for adjustment connected to the power supply terminal 3, the power input terminal 8, the output terminal 6, and the output for opening and closing the pulse current connected to the duty ratio adjusting circuit 13 according to the duty ratio specified by the variable resistor 14 for adjustment. And a switching transistor 15.

Next, the operation of the first embodiment of the present invention thus constructed will be described. FIG. 3 is a diagram showing operation timing in the first embodiment of the present invention.

The operation switch 9 is closed when operated by the driver or when the atmospheric temperature falls below a predetermined value (for example, 0 to -5 ° C). When the operation switch 9 is closed, power is supplied from the power battery 7 to the power input terminal 8, and at the same time, the power is connected to the indicator lamp 10 to light up and indicate that the device is in the operating state. From the power supply input terminal 8, as shown in FIG. 2, the semiconductor switch circuit 12, the duty ratio adjusting circuit 13, and the output switching transistor 1 are connected.
Power is supplied to 5.

On the other hand, the output from the drive circuit 1 is supplied to the control input terminal 5 of the pulse current generator 4 via the second backflow prevention diode D ₂ and also via the first backflow prevention diode D ₁ . Then, the solenoid valve drive current is supplied to the drive winding 3 of the solenoid valve 2.

When the drive circuit 1 is not operating, there is no control input at the control input terminal 5 of the pulse current generator 4.
At this time, the semiconductor switch circuit 12 is configured to be closed. Therefore, the semiconductor switch circuit 12 sends the output from the oscillator 11 to the duty ratio adjusting circuit 13. The duty ratio adjusting circuit 13 receives this output,
The output is supplied to the base electrode of the output switching transistor 15 at a duty ratio preset by the adjustment variable resistor 14. The collector electrode of the output switching transistor 15 is supplied with power from the power input terminal 8, so that the base electrode receives an output each time.
A pulse current is supplied from the emitter electrode to the drive winding 3 of the solenoid valve 2 via the output terminal 6 and the third backflow prevention diode D ₃ .

As shown in FIG. 4, the duty ratio P is T (m sec) for the pulse period and T _ON (m se) for the pulse generation time.
c), when the pulse stop time is T _OFF (m sec),

[0025]

(Equation 1) Is defined by Here, assuming that the current (rated current) when the reference voltage (24 V) is applied is I ₀ , the duty ratio P
The average current [outer 1] supplied by

[0026]

[Outside 1]

[0027]

(Equation 2) Is required.

For example, assuming that the duty ratio below the operating limit of the solenoid valve 2 is set, T _ON = 1 (m sec), T _OFF
= 2 (m sec), the duty ratio P is

[0029]

(Equation 3) When the reference voltage V ₀ = 24 (V), the average current [outer 1] is

[0030]

(Equation 4) Becomes

Therefore, when the solenoid valve 2 is not in operation, it is equivalent to supplying a current which is one third of the reference voltage, whereby the temperature at which freezing can be prevented can be maintained.

Here, it is assumed that the operation limit current of the solenoid valve 2 is 67%, for example. That is, 0.6 in the drive winding 3.
When a current of 7I ₀ or more is supplied, the solenoid valve 2 operates,
If it is less than that, it does not work. The above 0.333I ₀ is a current below this operating limit.

When a drive current is supplied from the drive circuit 1 to the drive winding 3 to operate the solenoid valve 2, the control input terminal 5 of the pulse current generator 4 receives the control input,
As shown in FIG. 3, the semiconductor switch circuit 12 is brought into the released state with a very short delay time t ₀ . As a result, the output from the oscillator 11 to the duty ratio adjusting circuit 13 is cut off, and the pulse current output to the drive winding 3 is stopped.

When there is an output from the drive circuit 1 when the pulse current supply is stopped, the pulse current generator 4 receives the output and after a predetermined delay time t (for example, several msec) has elapsed, the semiconductor The switch circuit 12 is closed.
Since the plunger return operation of the solenoid valve 2 is performed within this delay time t, the pulse current is supplied in a state where the solenoid valve 2 is operating reliably.

Since the switching of the pulse current supply is performed by the semiconductor switch circuit 12 as described above, the electrical contact of mechanical construction is unnecessary, and therefore the operation noise can be eliminated altogether.

(Second Embodiment) FIG. 5 is a block diagram showing the overall construction of the second embodiment of the present invention, and FIG. 6 is a block diagram showing the construction of a pulse current generator in the second embodiment of the present invention.

In the second embodiment of the present invention, the second backflow prevention diode D ₂ is removed from the configuration of the first embodiment, and further,
A pulse current generator 4a from which the control input terminal 5 which is the connection terminal and the semiconductor switch circuit 12 are removed is provided. That is, the circuit is simplified.

In the case of the second embodiment, regardless of whether or not the current is supplied from the drive circuit 1 to the drive winding 3 of the solenoid valve 2,
A pulse current is supplied from the pulse current generator 4a to the drive winding 3 at a duty ratio equal to or less than the operation limit of the solenoid valve 2. However, when the drive current is supplied from the drive circuit 1 to the drive winding, the potential of the output terminal 6 of the pulse current generator 4a is lower than the output of the drive circuit 1 by the voltage drop of the output switching transistor 15. No pulse current is substantially output from the output terminal 6. Therefore, as a result, the operation is performed as in the first embodiment. Since the number of component parts can be reduced, there is an advantage that the manufacturing cost can be reduced.

[0039]

As described above, according to the present invention, the solenoid valve for controlling the pressure of gas or liquid can be prevented from freezing with a simple structure, and the electric contact can be eliminated to prevent the contact from freezing. It is possible to completely eliminate the operation sound of contacts and contacts. Further, since it can be realized by a relatively inexpensive semiconductor switch, the power consumed for freezing prevention can be reduced, and the unevenness of the power supply battery can be eliminated. The device according to the present invention is effectively applied to a large automobile having a 24V power supply system. The present invention is ABS
It is useful when carrying out. That is, ABS is effective in preventing slippage during freezing, and according to the present invention, ABS is
Can be operated properly at low temperature.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a pulse current generator in the first embodiment of the present invention.

FIG. 3 is a diagram showing operation timing in the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a duty ratio of a pulse voltage according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing the overall configuration of a second embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration example of a pulse current generator in a second embodiment of the present invention.

[Explanation of symbols]

1 Drive Circuit 2 Solenoid Valve 3 Drive Winding 4, 4a Pulse Current Generator 5 Control Input Terminal 6 Output Terminal 7 Power Battery 8 Power Input Terminal 9 Actuation Switch 10 Indicator Light 11 Oscillator 12 Semiconductor Switch Circuit 13 Duty Ratio Adjustment Circuit 14 Adjustment Variable resistor for output 15 Output switching transistor D ₁ First backflow prevention diode D ₂ Second backflow prevention diode D ₃ Third backflow prevention diode

Claims (5)

[Claims] 1. A pulse current generator is provided for supplying a pulse current to the drive winding at a duty ratio equal to or less than an operation limit of the solenoid valve when the drive current is not supplied from the drive circuit to the solenoid valve drive winding. An antifreezing device for a solenoid valve, which is characterized in that 2. The pulse current generator comprises a control input terminal, the output voltage of the drive circuit is connected to the control input terminal, and the pulse current output is stopped for a period during which the output voltage is supplied. The antifreezing device for a solenoid valve according to claim 1, further comprising: 3. A first backflow prevention diode (D ₁ ) in the forward direction for the drive current is connected to the path for supplying the drive current to the drive winding, and a forward direction first reverse current prevention diode (D ₁ ) is connected to the output voltage of the drive circuit. The antifreezing device for a solenoid valve according to claim 2, wherein a _second backflow prevention diode (D ₂ ) is connected. 4. The inhibiting means operates immediately when a voltage is supplied to the control input terminal and is deactivated after a delay time t after the voltage at the control input terminal disappears. Anti-freezing device. 5. The pulse current generator is configured to continuously operate even while the drive current is being supplied, and a pulse current generator is provided in a path that supplies the output pulse current to the drive winding. The antifreezing device for a solenoid valve according to claim 1, further comprising a _third backflow prevention diode (D ₃ ).