JPH0572532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a torque control device for a brake tester.

BACKGROUND ART As one of the performance tests for vehicle brakes, there is a braking test for evaluating braking performance. This braking test apparatus has the configuration shown in FIG. The rotating drum (or disk) 1A of the test brake 1 is rotated together with the flywheel 2 at a set rotation speed by the drive electric motor 3, and by hydraulically operating the brake shoe 1B, the drum 1A is rotated according to the set torque. Then apply braking and measure the time until the drum 1A stops.

The braking torque control device controls the torque setting value of the torque setting device 4 and the brake shoe 1 using the load cell 5.
It is configured as an automatic torque control system that compares the detected torque value of B. That is, the deviation between the torque setting value and the detected torque value is calculated by the torque control amplifier 6 and converted into a hydraulic pressure command, and this hydraulic pressure command and the brake shoe 1
The deviation from the detected value of the operating oil pressure detector 7 of B is calculated by the oil pressure control amplifier 8 and made into a stroke command,
This stroke command and the hydraulic pressure generation master cylinder 9
The deviation from the detected value of the stroke detector 10 is calculated by the stroke control amplifier 11 and used as an operation signal for the operation cylinder 12, and the hydraulic pressure supplied by the operation cylinder 12 to the master cylinder 9 is controlled in accordance with this operation signal. In this way, the automatic torque control system has a hydraulic control system and a stroke control system in the minor loop, and applies braking torque according to the set torque between the brake shoe 1B and the drum 1A.

In the conventional automatic torque control device, when the braking progresses and the rotational speed of the brake drum reaches zero or approaches zero, the torque value detected by the load cell 5 becomes zero. This may not be the actual rotation speed of zero, but may be zero due to insufficient resolution. At this time,
The control loop becomes equivalent to an open loop, the output (hydraulic pressure command) of the torque control amplifier 6 becomes the maximum limiter value, and the hydraulic control amplifier 8
When the maximum limiter value reaches 100%, the oil pressure increases rapidly to 100%. This phenomenon occurs when the master cylinder 9
A shock is applied to the hydraulic pipes, the test brake 1, and the test brake 1. Furthermore, if the hydraulic pressure allowed by the test brake 1 is small, there is a risk that the brake 1 will be damaged.

In order to eliminate this inconvenience, conventionally a detector for detecting the rotation speed of the brake drum 1A and a comparator for forcibly controlling the hydraulic control amount to zero when the detected value of this detector becomes zero. I am trying to set it up.

Problems to be Solved by the Invention However, in the past, the hydraulic control amount was set to zero at an actual rotation speed of 10 rpm to several rpm due to the detection accuracy of the rotation speed detector and the operation delay time. As shown in Figure 4, this kind of brake-off control is such that at the start of braking, both the torque (b in the figure) and oil pressure (c in the figure) are at the set values, and the rotational speed (a in the figure) decreases at a constant slope. When the number of revolutions reaches several revolutions (when the time
At t ₁ ), hydraulic pressure (zero torque) control is performed using a comparator. Therefore, after the oil pressure is zero, the flywheel 2 comes to a natural stop due to free rotation.
When the inertia of the motor is large, it continues to rotate for a long time, delaying the next test, resulting in an inefficient test, and it also makes accurate measurement difficult, as errors occur in braking time measurements.

Means for Solving the Problems The present invention includes a comparator that detects when the detected value of the rotation speed detector becomes close to zero, a memory that stores the oil pressure detected value at the time of detection by the comparator, and a Later, a hydraulic pressure command means is provided for controlling the hydraulic pressure according to the values stored in the memory.

Function: By continuing the oil pressure control amount immediately before detection using the comparator output detected by the rotation speed detector, stop control is performed using the same braking force while suppressing a sudden increase in oil pressure.

Embodiment FIG. 1 is a main circuit diagram showing an embodiment of the present invention. The torque control amplifier 6 compares the setting value of the torque setting device 4 with the torque detection value of the load cell 5, calculates the deviation by proportional integration, and obtains a hydraulic pressure command output.
The hydraulic control amplifier 8 performs calculations by comparing the hydraulic pressure command with the detected value of the hydraulic pressure detector 7. Here, the torque control amplifier 6 includes a limiter circuit including a diode D ₁ and resistors R ₁ and R ₂ , and the limiter value of this limiter circuit is set by the output voltage of the buffer amplifier 21 . The output voltage of the buffer amplifier 21 is normally set at the set value _L1 of the limiter setter 22, and is switched to the set value _L2 by the analog changeover switch 23 when zero rotation speed is detected. The set value _L2 is controlled by the following configuration.

A comparator 25 compares the detection value of the rotation speed detector 24 that detects the rotation speed of the brake drum with the rotation speed zero setting value _OSET , and the drum rotation speed is determined to be the zero setting value.
When the voltage drops to O _SET , an inverted output is taken out to the comparator 25. The output of the comparator 25 is used as a storage instruction for the memory 26 and also as a switching instruction for the changeover switch 23 to the set value _L2 side. The memory 26 stores and holds the detection signal of the oil pressure detector 7 in response to a storage command from the comparator 25, and continues to output this storage signal as the set value _L2 .

The operation of such a configuration will be explained with reference to FIG. At the start of the braking test, the torque control amplifier 6 issues a hydraulic pressure command so that the braking torque (Fig. 2b) corresponds to the torque setting value of the torque setting device 4, and the hydraulic control amplifier 8 outputs a hydraulic pressure command according to the torque. (Figure 2c) Issue a stroke command. This braking causes the brake drum 1A to rotate at a rotational speed (second
Figure a) is descending at a constant slope. Then, when the rotation speed drops to the set value O _SET (time t ₁ ),
The detection output is taken out by the comparator 25, the oil pressure at that time is stored in the memory 26, and this oil pressure signal becomes the limiter value of the torque control amplifier 6 as the set value _L2 . Therefore, even after the rotation speed has decreased to the set value O _SET , the hydraulic pressure command, that is, the output of the torque control amplifier 6 continues to be controlled by the limiter value L ₂ , and even if the detection resolution of the load cell 5 is insufficient, the limiter value L ₂ remains unchanged. Torque control that is limited to this prevents a sudden increase in oil pressure as in the prior art, and provides quick stop control using limited oil pressure. Also,
After a complete stop when the rotation speed reaches zero, the oil pressure is limited.

In the embodiment, a case is shown in which the limiter value of the torque control amplifier 6 is switched when the rotation speed decreases to the set value O _SET , but in this case, the output of the memory 26 is changed to the output of the torque control amplifier 6 and the hydraulic pressure is directly changed. The same effect can be obtained by using a circuit configuration that gives the control amplifier 8 as a hydraulic pressure command.

Effects of the Invention According to the present invention, since the oil pressure at that time is used as the command value or limit value of the oil pressure control system when the rotation speed is detected near zero, a sudden increase in oil pressure is suppressed even though the torque control system becomes an open loop. However, it enables quick stopping to rotational stop and accurate braking performance tests at the same descent rate.

[Brief explanation of the drawing]

FIG. 1 is a main circuit diagram showing an embodiment of the present invention;
Fig. 2 is an operation waveform diagram for explaining the operation of Fig. 1;
FIG. 3 is a configuration diagram of a torque control device for a brake tester, and FIG. 4 is an operation waveform diagram for explaining conventional operation. 1... Test brake, 2... Flywheel,
3... Electric motor, 4... Torque setting device, 5... Load cell, 6... Torque control amplifier, 7... Oil pressure detector, 8... Oil pressure control amplifier, 21... Buffer amplifier, 22... Limiter setting device, 23... Selector switch, 24... Rotation speed detector, 25... Comparator, 26... Memory.

Claims (1)

[Claims] 1. A torque control device for a brake tester that obtains a hydraulic pressure command from a torque control amplifier by comparing a torque setting value and a torque detection value, and controls the operating hydraulic pressure of a test brake by comparing this hydraulic pressure command and a hydraulic pressure detection value. , a comparator for detecting that the detection value of the rotation speed detector of the test brake has become near zero, a memory for storing the oil pressure detection value at the time of detection by the comparator, and a memory for storing the oil pressure detection value after detection by the comparator. 1. A torque control device for a brake tester, comprising: hydraulic pressure command means for controlling hydraulic pressure according to a stored value.