JPH035880Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an engine cooling water temperature control device in an engine testing device.

On an engine production line, various performance tests of assembled engines require testing while supplying cooling water at a predetermined temperature (80° C.) to the assembled engines. For this reason, in the test room, a heater is installed in the cooling water channel that supplies the cooling water from the cooling water tank to the engine unit, and the heater controls the heating of the cooling water to supply cooling water at a predetermined temperature.

A conventional temperature control device has a configuration shown in FIG. The set value of the cooling water temperature setting device 1 and the detected value of the cooling water temperature are compared, and a proportional differential calculation is performed by a proportional amplifier 2 and a differential amplifier 3, and this output is proportional and integrated by a proportional integral amplifier 4 with a limiter. The signal is passed through a deviation proportional amplifier 5 and is used as an on/off control signal for a thyristor switch 6. The deviation proportional amplifier 5 obtains an on/off ratio control output for controlling the off control time after the on control of the thyristor switch 6 for a certain period of time (for example, 1 second) in accordance with the positive and negative input levels thereof, by feedback using a minor lube. The thyristor switch 6 energizes the heater 8 from the power source 7 during its on period. proportional integral amplifier 4
is a variable resistor 4 for the negative change of its output V ₀
The lower limit of cooling water cooling by A and diode 4B,
In other words, the limiter value is set such that the OFF period of the thyristor switch 6 is the longest and the cooling water temperature is lowered, and when the output V ₀ changes in the positive direction, the variable resistor 4C and the diode 4D are used to increase the cooling water temperature. The upper limit, that is, the limiter value that increases the cooling water temperature by shortening the off period of the thyristor switch 6 is set.

In such a configuration, the cooling water supply means for the engine alone is connected, and the operation of the temperature control device is started at the same time as the cooling water supply starts. At this time, since the temperature of the cooling water is considerably lower than the set temperature (80℃), there is a large difference between the set value of the setting device 1 and the detected temperature, and the output V ₀ of the comparator and integral amplifier 4 is as shown in Figure 2. The average energization amount of the heater 8 is maximized by being limited to +10V in the direction, and the cooling water temperature T is heated toward the set temperature of 80°C. When the temperature of the cooling water approaches 80° C., the proportional-integral amplifier 4 drops from the limiter value and returns to proportional-integral control of energization, but an overshoot occurs in which the cooling water temperature T rises too much due to residual heat from heating by the heater 8. In this overshoot, the output _V0 of the amplifier 4 goes to the negative side, lowering the energization rate to the heater 8, lowering the heating of the cooling water, and controlling the heater so that it gradually reaches the set temperature.

In this way, with conventional equipment, the overshoot of overheating the cooling water becomes large, which increases the time it takes for the cooling water to settle to the set temperature, and the waiting time before engine test measurements increases, which reduces the time required for the test. I had a problem that took a long time.

The purpose of this invention is to provide a temperature control device that can quickly control the cooling water temperature to the set temperature by lowering the energization rate of the heater before the cooling water temperature reaches the set temperature at the start of cooling water heating. shall be.

FIG. 3 is a circuit diagram showing an embodiment of the present invention, and parts that are the same as those in FIG. 1 or have the same functions are given the same reference numerals, and their explanation will be omitted. A constant negative voltage (-V) is applied to the variable resistor 4C of the proportional-integral amplifier 4 via the normally closed contact 9A of the relay 9.
connected to. The relay 9 is controlled on/off by the on/off output of the comparator 10. Comparator 1
For a comparison input of 0, the set temperature and detected temperature, which are the same as the set value of the offset setter 11 and the set value of the setter 1, are compared. The set value of the offset setter 11 is made to have the same polarity as the detected temperature. And comparator 1
When the detected temperature is lower than the set temperature of 0 (80° C.) and the difference reaches the set value of the setting device 11, it turns on and energizes the relay 9. To energize this relay 9, contact 9A is opened, and the output of proportional-integral amplifier 4 is
The positive limiter value of V ₀ is reduced to the edge layer voltage of diode 4D.

Therefore, as shown in Fig. 4, when the cooling water starts to be heated, the detected temperature is very low compared to the set temperature (80°C), so the output of the comparator 10 is turned off and the relay 9 is deenergized. The contact point 9A is closed, and the cooling water is heated at the same heating rate as the conventional device, and even at a higher heating rate. When the difference between the cooling water temperature and the set temperature reaches the offset value set in the setting device 11 during this heating, the comparator 10 is turned on and the relay contact 9A is opened. FIG. 4 shows a case where the set value of the offset setter 11 is set to a value corresponding to 10°C.

By opening the relay contact 9A, the output V ₀ of the proportional-integral amplifier 4 is limited to the lining voltage of the diode 4D, and a control state is entered in which the energization rate of the heater 8 is lowered and heating of the cooling water is almost stopped. Even in this state, the cooling water temperature rises due to residual heat from the heater and reaches the set temperature. After the relay contact 9A is opened, the cooling water temperature is made to match the set temperature while maintaining control that limits the heater energization rate to the value of the diode 4D in the positive direction. In this way, when the detected temperature of the cooling water relative to the set temperature is lower than the offset set value, the heating limiter value is increased to speed up the heating to near the set temperature, and when the temperature falls within the offset set value, the limiter value is increased. By lowering the limiter value, heating is performed to the set temperature with less overshoot due to heater residual heat, and subsequent temperature control is performed using a lower limiter value.

In conventional constant limiter value control, if the limiter value is increased, the heating time from the start of heating to the set temperature can be shortened, but when the temperature approaches the set temperature and the limiter value is below the normal proportional-integral control. However, due to the delay in the system, the heater energization rate becomes relatively high until the detected temperature is very close to the set value, and even exceeds the set value, causing a high overshoot due to high heater residual heat, and the reverse occurs. In order to suppress overshoot, the limiter value is set low and the heating time becomes longer. In this point,
In this example, the heating time is shortened by setting a high limiter value from the start of heating until it is close to the set temperature (set by the offset setting value), and before the set temperature is reached, the limiter value is switched to a lower limiter value in advance to allow heating by the heater's residual heat. It is possible to prevent the cooling water from greatly exceeding the set temperature, that is, to prevent a high overshoot from occurring.

Note that the upper limiter value of the proportional-integral amplifier 4 is not limited to the layer voltage of the diode 4D, and the design can be changed as appropriate, such as by switching the variable resistor 4C to another variable resistor using the relay 9. Further, the temperature control amplifier circuit is not limited to the configuration of each of the amplifiers 2 to 4, but may be configured to switch the limiter of an amplifier equipped with a limiter.

As described above, according to the present invention, the energization rate of the heater is relatively high at the beginning of cooling water heating, that is, higher than the energization rate of the conventional device, enabling rapid heating to near the set temperature. In order to reduce overshoot and control the cooling water temperature to the set temperature by reducing the energization rate of the heater when the cooling water temperature is close to the set temperature and using the heater's residual heat at a relatively low heating rate,
This has the effect of significantly shortening the time required to heat the cooling water.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional temperature control device, Fig. 2 is a control mode diagram at the start of the control shown in Fig. 1, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 is a diagram of Fig. 3. FIG. 1...Temperature setting device, 2...Proportional amplifier, 3...
Differential amplifier, 4... Proportional-integral amplifier, 5... Deviation proportional amplifier, 6... Thyristor switch, 8...
Heater, 9... Relay, 10... Comparator, 11...
...Offset setting device.

Claims (1)

[Scope of utility model registration request] In a temperature control device that controls the cooling water supplied to the engine from the cooling water tank for engine unit tests to a set temperature by controlling the energization rate of the heater, input according to the deviation between the set temperature and the detected temperature of the cooling water is used. Temperature control amplifiers 2, 3, and 4 with limiters that amplify and have upper and lower limiter values set, and control the energization rate of the heater according to the level of the upper limiter value and lower limiter value range of these amplifiers. On/off control means 5, 6, a comparator 10 for detecting whether the detected temperature of the cooling water is lower than the offset set value with respect to the set temperature, and a comparator 10 for detecting whether the output of this comparator is lower than the offset set value. The present invention is characterized by comprising a switching means 9 for increasing the upper limiter value of the temperature control amplifier when the temperature control amplifier is lowered and lowering the upper limiter value when the output of the comparator is detected to be within an offset set value. Engine coolant temperature control device.