JPH04126652A - Electropneumatic change valve amplifier - Google Patents

Abstract

PURPOSE:To certainly prevent the current conduction to an electropneumatic change valve when it is in trouble thus preventing the valve from burning by constituting a titled electropneumatic change valve amplifier in such a way that when the desired control current value of an electropneumatic change valve is larger than the actual current value of the electropneumatic change valve, a transistor is turned on to actuate the electropneumatic change valve connected to the secondary coil of the transistor. CONSTITUTION:When ep(control command value voltage) corresponding to a desired EP valve current value > ef(feedback voltage), that is, when electropneumatic change valve EPV(EP valve) current is smaller than the desired EP valve current value, the output of a comparator Cp reaches up to H level, and base current flows from a control power supply P1 to the base of a transistor Q1 through a resister R3 to turn the transistor Q1 on. This causes the flow of the collector current on the primary side of a pulse transformer T1 thus generating voltage on the secondary side of the pulse transformer T1. This leads to the supply of power supply to the base of a transistor Q2 thus turning the transistor Q3. EP valve current is thus increased. On the other hand, if a control power supply P1, for example, lapses, the transistor Q1 is not turned on, therefore, the transistor Q2 is not turned on, too thus the current conduction to the EP valve is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention applies to electro-pneumatic conversion valves (hereinafter E
This relates to an EP valve amplifier that drives an EP valve (referred to as a P valve). □ [Prior Art] FIG. 3 is a circuit diagram of a conventional electro-pneumatic conversion valve amplifier l shown, for example, in Publication Technique No. 89-4071. When ep (control command value voltage) corresponding to the EP valve current control target value (hereinafter referred to as target E2 valve current value) > ef (feedback voltage), that is, when the EP valve current is smaller than the target EP valve current value. The output of comparator Cp becomes L level.

This ef (feedback voltage) is generated by being fed back to the EP valve current comparator Cp by the current detection resistor R5. When the output of the comparator Cp becomes L level, the base of the transistor Q1 becomes the ground potential, and the transistor Q+ is turned off.

As a result, the vehicle's battery power P2 (usually DC 100V) is supplied to the base of the transistor Q2 via the resistors R2 and R3, turning on the transistor Q2 and supplying power to the EP valve EPV.

Also, ep<ef; that is, EP
When the valve current is large, the transistor Q1 is turned on and the transistor Q2 is turned off, contrary to the above, and the power supply to the EP valve EPV is cut off.

By repeating the above operations, the EP valve current control is controlled to match the target value.

[Problem to be solved by the invention] In the conventional electro-pneumatic conversion valve amplifier as described above, the control power supply P1
In the case of invalidation or an off-failure of transistor Q+, the above-mentioned state of ep<ef occurs, and when transistor Q2 should normally be turned off, transistor Ql cannot be turned on, and transistor Q2 remains on.

In such a case, since current always flows to the EP valve EPV, the pneumatic pressure output of the EP valve becomes abnormally excessive. Further, since the battery power source P2 normally uses DC 100V, there are problems such as a long time due to the large power.

This invention was made in order to solve the above-mentioned problems, and it is a railway vehicle power supply that does not burn out the EP valve EPV and the transistor Q2 when the control power supply Pi expires or when the transistor Q+ turns off. The purpose is to obtain an air conversion valve amplifier.

[Means for Solving the Problems] The electro-pneumatic conversion valve amplifier according to the present invention includes: a comparison means for substantially comparing a control target electro-pneumatic conversion valve current value and an electro-pneumatic conversion valve current value; a first transistor that is turned on by the output of the comparator when current value>electro-pneumatic conversion valve current value; a transformer whose primary winding is connected in series with the output circuit of the first transistor; and the transformer. a second transistor connected to the secondary winding of the second transistor, which is turned on by the on-output of the first transistor, and operates an electro-pneumatic conversion valve.

[Operation] When the control target electro-pneumatic conversion valve current value is larger than the actual electro-pneumatic conversion valve current value, the first transistor is turned on and its output current flows to the primary winding of the transformer. A voltage is generated in the secondary winding, the second transistor connected to the secondary winding is turned on, and the electro-pneumatic conversion valve is operated.

[Embodiment] An electropneumatic conversion valve amplifier l for a railway vehicle according to the present invention will be explained using FIG. 1 showing a circuit diagram of an embodiment thereof.

In the figure, ep (control command value voltage) corresponding to the EP valve current control target value (hereinafter referred to as target EP valve current value)>e
f (feedback voltage), that is, when the electro-pneumatic conversion valve EPV (hereinafter referred to as EP valve) current is smaller than the target EP valve current value, the output of the comparator Cp becomes H level. above ef
(Feedback voltage) is generated by being fed back to the EP valve current comparator Cp by the current detection resistor R5.

That is, although the comparator Cp compares voltages, it is essentially a comparison means that compares the target EP valve current value and the actual EP valve current value. When the output of the comparator Cp becomes H level, a base current flows from the control power supply P1 to the base of the transistor Q+ via the resistor R3, turning on the transistor Q1. As a result, the collector current of the transistor Q+ flows to the primary side of the pulse transformer T1, so the pulse transformer T
A voltage is generated on the secondary side of the transistor Q2, power is supplied to the base of the transistor Q2, the transistor Q2 is turned on, and the EP valve current increases.

Conversely, 6p< ef, that is, E for the target EP valve valve type current value.
When the P valve current is large, the output of comparison WCp becomes L level. As a result, the base of the transistor Ql becomes the ground potential, and the transistor Ql is turned off. Therefore, the transistor Q+ flowing to the primary side of the pulse transformer Tl
The collector current of becomes zero. At this time, the diode DR absorbs the surge voltage generated in the primary coil of the pulse transformer T1. Therefore, the voltage on the secondary side of the pulse transformer T1 also becomes zero, the voltage at the base of the transistor Q2 also becomes zero, the transistor Q2 is also turned off, and the EP valve current decreases.

As described above, by repeating the increase and decrease of the EP valve current in a certain period, the EP valve current is controlled to match the target EP valve current value. This control situation is shown in FIG. FIG. 2 shows the input and output states of the comparator cp and the on and off states of the transistors Qs and Q2.

Further, the above period is determined by other circuit constants such as the inductance of the EP valve used and the drive voltage. In addition,
The pulse transformer Tl is a transistor QI according to this period.
It goes without saying that it is necessary to select one that has saturation characteristics with sufficient margin for the on-time.

In this circuit, when the control power supply Pl expires, the transistor Q1 ep,! : Never turns on regardless of ef relationship. That is, since the transistor Ql is not turned on, the transistor Q2 is also not turned on, so that no current flows to the EP valve. Also, in the case of an OFF failure of the transistor Q+, the same is true, and no current flows to the EP valve.Also, even if the transistor Ql is an ON failure, the ON time of the pulse transformer Tl is
When the saturation characteristic of the transistor Q2 is exceeded, the base voltage of the transistor Q2 disappears, so the transistor Q2 does not continue to be turned on. Therefore, current does not continue to flow through the BP valve.

[Effects of the Invention] The electro-pneumatic conversion valve amplifier of the present invention causes current to flow through the electro-pneumatic conversion valve by turning on the second transistor via the transformer due to the ON output of the first transistor. Therefore, even if the control power source for the first transistor expires or a failure occurs in which the first transistor remains off or on, current will not continue to flow through the electro-pneumatic conversion valve. Therefore, in the case of the above failure, there is no possibility that the pneumatic output of the electro-pneumatic conversion valve becomes excessive or that electrical components such as the second transistor and the electro-pneumatic conversion valve are burned out.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an electropneumatic conversion valve amplifier for a railway vehicle according to an embodiment of the present invention, and FIG. 2 shows input/output states of comparator Cp and transistors Q1. FIG. 3, which shows the state of Q2, is a circuit diagram of a conventional electro-pneumatic conversion valve amplifier for railway vehicles. In the figure, 1 is an electropneumatic conversion valve amplifier, Cp is a comparator, and Q+. Q2 is a transistor, Tl is a pulse transformer, and EPV is an electro-pneumatic conversion valve.

Claims (1)

[Claims] (1) Comparison means for substantially comparing the control target electro-pneumatic conversion valve current value and the electro-pneumatic conversion valve current value, according to the comparator output when the control target electro-pneumatic conversion valve current value>the electro-pneumatic conversion valve current value. a first transistor to be turned on; a transformer having its primary winding connected in series to the output circuit of the first transistor; and a transformer having its primary winding connected to the secondary winding of the transformer to turn on the first transistor. An electro-pneumatic conversion valve amplifier comprising: a second transistor that is turned on by an on output and operates the electro-pneumatic conversion valve.