JPS64268B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable speed steering gear testing device for a tracked vehicle, which tests on a bench the running characteristics and turning characteristics of a variable speed steering gear provided in a tracked vehicle.

Fig. 1 shows a conventional test device of this kind, in which the input shaft side of the variable speed steering gear 1 is connected to a prime mover 2 such as an engine.
The left and right output shaft sides are connected to hydraulic pump motors 3, 3' for driving or absorbing power.
When the hydraulic pump/motor 3, 3' absorbs power, that is, when the hydraulic pump/motor is operated as a hydraulic pump, the hydraulic pump uses the variable speed steering gear 1 as a power source and uses the hydraulic oil in the tank 8. Suction is carried out through hydraulic lines a, a', check valves 7, 7' and hydraulic lines b, b', and discharge pressure in hydraulic lines c, c' is adjusted by relief valves 4, 4'.
At this time, the relief valves 4, 4' are controlled by external pilot pressures p, p' to set the discharge pressure of the hydraulic pump motors 3, 3'.

In addition, the hydraulic pump motor 3, 3' is driven by a
That is, when operating as a hydraulic motor, pressure oil from hydraulic pumps 5, 5' driven by electric motors 6, 6' is supplied to the hydraulic pumps via hydraulic conduits d, d' and b, b'. At this time, the relief valve 4,
4' is set so that the pilot pressure p' is zero and no load pressure is applied. Further, the rotational speed of the hydraulic motor can be adjusted by changing the tilt angle of the hydraulic pumps 5, 5'.

However, in the test equipment configured as described above, the output speed of the variable speed steering gear is slow, and furthermore, when absorbing power, the discharge amount of the hydraulic pump/motor 3, 3' is small and it is difficult to control the load torque. Since the pressure of the relief valves 4, 4' cannot be set accurately, it is difficult to set a stable load torque.

Further, in many cases, a plunger type hydraulic pump/motor is used, but at low speeds, the pressure oil pulsates a lot and load torque is generated in accordance with this pulsation, so it is not possible to apply load torque with high accuracy.

In view of the above points, the present invention provides a speed change control system for tracked vehicles that improves the accuracy of power absorption and allows stable load torque to be applied even when the output speed of the speed change steering system under test is slow. The purpose is to provide a machine testing device.

An embodiment of the apparatus of the present invention will be described below with reference to the drawings.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts.

9, 9' are hydraulic pipes b, b', d, between the hydraulic pump/motor 3, 3' and the hydraulic pump 5, 5'.
The hydraulic switching valves 9, 9' are electromagnetic hydraulic switching valves installed in the middle of d', and these hydraulic switching valves 9, 9' connect the discharge side of the hydraulic pumps 5, 5' to the relief valves 4, 4' when absorbing the power of the variable speed steering gear 1. Hydraulic pump/motor 3 from upstream of
When the variable speed steering gear 1 is powered, the hydraulic pipes d and d' on the discharge side of the hydraulic pumps 5 and 5' are switched to the hydraulic pipes c and c' on the discharge side of the hydraulic pumps 5 and 5'. Switch to hydraulic pipes b and b' on the suction side of 3'.

Next, the operation of the test device of the present invention will be explained.

First, in a test in which the power of the variable speed steering gear 1 of the specimen is absorbed by the hydraulic pump motor 3, 3',
Using the variable speed steering gear 1 as a power source, the hydraulic pump pumps the hydraulic oil in the tank 8 to the hydraulic pipes a, a', the check valve 7,
7' and by suction via hydraulic lines b, b'. At this time, the hydraulic pumps 5, 5' are operated, the hydraulic switching valves 9, 9' are switched from the position to the position (the state shown in Fig. 2), and the hydraulic pipes d,
Since d' and hydraulic pipes e and e' are connected, pressure oil pipes d and d' from hydraulic pumps 5 and 5', hydraulic switching valves 9,
9' and hydraulic lines e, e' to the hydraulic lines c, c' on the discharge side of the hydraulic pump. Therefore, even if the output speed of the variable speed steering gear 1, that is, the output speed of the hydraulic pump is low and there is little pressure oil on the discharge side, the relief valves 4, 4' are equipped with the hydraulic pump 5,
Since the pressure oil from 5' is added and a large amount of pressure oil flows in, the pressure setting of the relief valves 4 and 4' can be performed with high accuracy.

In addition, in a test in which the power of the variable speed steering gear 1 of the specimen is driven by the hydraulic pump motor 3, 3',
Since the hydraulic switching valves 9, 9' are switched from position to position, the pressure oil discharged from the hydraulic pumps 5, 5' is transferred to the hydraulic pipes d, d', the hydraulic switching valves 9, 9', and the hydraulic pressure as in the conventional case. The hydraulic motor is operated because it is supplied to the hydraulic motor via pipes b and b'.

The variable speed steering gear test device for tracked vehicles of the present invention consists of a hydraulic pump/motor connected to both output shaft sides of the variable speed steering gear of the test object, and a hydraulic pump that supplies pressure oil to the hydraulic pump/motor. In the middle, there is a hydraulic switching valve that switches the discharge side of the hydraulic pump from upstream of the relief valve to the discharge side of the hydraulic pump/motor when absorbing power, and switches the discharge side of the hydraulic pump to the suction side of the hydraulic pump/motor when driving power. By providing this, even if the output speed of the variable speed steering gear of the test object is slow, the accuracy during power absorption can be improved and stable load torque can be applied.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a hydraulic circuit in a conventional variable speed steering gear testing device for a tracked vehicle, and FIG. 2 is a diagram showing a hydraulic circuit in a variable speed steering device testing device for a tracked vehicle according to the present invention. 1... Variable speed steering gear, 3, 3'... Hydraulic pump.
Motor, 5, 5...Hydraulic pump, 9,9'...Hydraulic switching valve.

Claims (1)

[Claims] 1. A hydraulic pump motor that is connected to both output shaft sides of the variable speed steering gear and that absorbs or drives power;
In this variable speed steering gear test equipment for tracked vehicles equipped with a hydraulic pump that supplies pressure oil to the hydraulic pump/motor, a hydraulic pump discharge valve is installed in the middle of the pipeline between the hydraulic pump/motor and the hydraulic pump when the hydraulic pump is absorbing power. A tracked vehicle characterized by being provided with a hydraulic switching valve that switches the side from the upstream side of the relief valve to the discharge side of the hydraulic pump/motor, and switches the discharge side of the hydraulic pump to the suction side of the hydraulic pump/motor when driving power. Variable speed steering gear testing equipment.