Test equipment

Abstract

The present invention provides a test apparatus that can shorten the test preparation time, from the start of the hydraulic motor to the point where the device is ready for testing. [Solution] The test apparatus 1 of the present invention is a test apparatus 1 that can apply a load torque in the opposite direction to the rotation direction of the hydraulic motor 2 to the rotating shaft 2a of the hydraulic motor 2, and comprises a hydraulic pump (hydraulic pump) 6 that supplies working fluid to the hydraulic motor 2, an electric motor 7 that drives the hydraulic pump (hydraulic pump) 6, and a controller 4 that controls the electric motor 7, wherein the controller 4 reduces the rate of increase of the rotation speed of the hydraulic motor 2 at the end of the period from when the hydraulic motor 2 is started to rotate until the rotation speed of the hydraulic motor 2 reaches the first test rotation speed (test rotation speed) indicated by the test conditions.

Description

Technical Field

[0001] The present invention relates to a test device.

Background Art

[0002] A conventional test device for testing a hydraulic motor connects an electric motor to the rotating shaft of the hydraulic motor via a coupling, supplies pressure oil from a hydraulic pump to the hydraulic motor to rotationally drive the hydraulic motor, and applies a load torque to the rotating shaft from the electric motor in the direction opposite to the rotation direction of the hydraulic motor, thereby creating an environment equivalent to the environment in which the hydraulic motor is actually used and testing the performance of the hydraulic motor (see, for example, Patent Document 1).

[0003] In such a test device, when performing a volumetric efficiency test, it is necessary to match the rotational speed of the hydraulic motor with the test rotational speed indicated by the test conditions. In the conventional test device, until the rotational speed of the hydraulic motor matches the test rotational speed after starting, the flow rate supplied to the hydraulic motor is increased at a constant rate to increase the rotational speed of the hydraulic motor at a constant acceleration rate (the rate of change of rotational speed with respect to time).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, in the conventional test device, if the acceleration rate of the rotational speed of the hydraulic motor is small, the time required for the rotational speed of the hydraulic motor to reach the test rotational speed becomes long, and the time required from the start of the hydraulic motor to the start of the test becomes long.

[0006] However, if the rate of increase in the hydraulic motor's rotational speed is increased too much, the time it takes for the hydraulic motor to reach the test rotational speed from startup will be shortened, but the hydraulic motor's rotational speed will overshoot the test rotational speed. Furthermore, if the flow rate of the hydraulic pump is reduced after the hydraulic motor's rotational speed has overshot the test rotational speed, the hydraulic motor's rotational speed will undershoot, and the hydraulic pump's rotational speed will hunt and become unstable.

[0007] Therefore, the present invention aims to provide a test apparatus that can shorten the test preparation time from the start of the hydraulic motor to the point where the test can be performed. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention provides a test apparatus capable of applying a load torque in the opposite direction to the rotation direction of a hydraulic motor to the rotating shaft of a hydraulic motor, comprising a hydraulic pump that supplies working fluid to the hydraulic motor, an electric motor that drives the hydraulic pump, and a controller that controls the electric motor, wherein the controller reduces the rate of increase of the rotation speed of the hydraulic motor at the end of the period from when the hydraulic motor is started to rotate until the rotation speed of the hydraulic motor reaches the test rotation speed indicated by the test conditions.

[0009] With a test apparatus configured in this way, the rate of increase in the hydraulic motor's rotational speed is reduced towards the end of the period from when the hydraulic motor is started to when it reaches the test rotational speed indicated by the test conditions. This allows for a higher rate of increase in the hydraulic motor's rotational speed, shortening the time required for the hydraulic motor's rotational speed to rise to near the test rotational speed. Furthermore, by reducing the rate of increase in the hydraulic motor's rotational speed thereafter, it is possible to suppress the hydraulic motor's rotational speed from overshooting the test rotational speed. Even if the rotational speed does overshoot the test rotational speed, the amount of overshoot is reduced, thus suppressing hunting, where the hydraulic motor's rotational speed becomes oscillating around the test rotational speed.

[0010] Furthermore, the test apparatus may gradually reduce the rate of increase of the hydraulic motor's rotational speed. When the test apparatus gradually reduces the rate of increase of the hydraulic motor's rotational speed in this way, even if the rate of increase of the hydraulic motor's rotational speed is increased further until the rotational speed of the hydraulic motor rises close to the test rotational speed, the rate of increase can be gradually reduced as the rotational speed of the hydraulic motor approaches the test rotational speed. This suppresses the hydraulic motor's rotational speed from hunting, and thus further shortens the test preparation time.

[0011] Furthermore, the test apparatus may be equipped with a flow sensor that detects the flow rate of the working fluid supplied from the hydraulic pump to the hydraulic motor, and the controller may monitor the flow rate of the working fluid detected by the flow sensor and control the rotational speed of the electric motor to adjust the rate of increase of the hydraulic motor. With a test apparatus configured in this way, compared to directly detecting the rotational speed of the hydraulic motor, the discharge flow rate of the hydraulic pump can be monitored using a flow sensor that is not affected by the efficiency or inertia of the hydraulic motor, thereby managing the flow rate of the hydraulic pump, allowing for accurate control of the hydraulic pump and easily reducing test preparation time. [Effects of the Invention]

[0012] The test apparatus of the present invention can shorten the test preparation time from the start of the hydraulic motor to the point where the test can be performed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing the configuration of a test apparatus in one embodiment. [Figure 2] This is a configuration diagram of the controller of a test apparatus in one embodiment. [Figure 3] This is a diagram showing the configuration of the pump control unit in the controller. [Figure 4] This diagram shows the rate of increase in rotational speed of a hydraulic motor. [Figure 5] This is a diagram illustrating the configuration of the motor control unit in the controller. [Figure 6] This is a flowchart illustrating an example of the processing procedure of the controller of a test apparatus in one embodiment. [Figure 7] This diagram shows the rate of increase when the rotational speed of a hydraulic motor is gradually reduced. [Figure 8] This flowchart shows another example of the processing procedure for the controller of the test apparatus in one embodiment. [Modes for carrying out the invention]

[0014] The present invention will be described below based on the embodiments shown in the figures. As shown in Figure 1, the test apparatus 1 in one embodiment is configured to include a hydraulic pump 6 which is a hydraulic pump that supplies pressurized oil as a working fluid to the hydraulic motor 2 which is the object of the test, an electric motor 7 which drives the hydraulic pump 6, and a controller 4 which controls the electric motor 7. The test apparatus is configured to test the hydraulic motor 2 by applying a load torque to the rotation shaft 2a of the hydraulic motor 2 that is in the opposite direction to the rotation direction of the rotation shaft 2a.

[0015] The following describes each part of the test apparatus 1. First, the hydraulic motor 2, which is the object of the test of the test apparatus 1, will be described. In this embodiment, the hydraulic motor 2 is equipped with a rotating shaft 2a for transmitting power to the outside and is a variable displacement hydraulic piston motor using working fluid as the working oil. Although not shown in the figures, it is equipped with a swash plate, a cylinder that drives the swash plate, and a solenoid valve for controlling the extension and retraction of the cylinder, and by changing the tilt angle of the swash plate, the displacement can be changed and the rotational speed can be changed even if the amount of working oil is constant.

[0016] Furthermore, the hydraulic motor 2 may be driven by a liquid other than hydraulic oil as the working fluid, and if it is a variable displacement type, it may be a vane motor in addition to a piston motor, in which the displacement can be changed by adjusting the eccentricity of the cam ring relative to the rotor. Also, since the test apparatus 1 can be used to test a fixed displacement type hydraulic motor, the hydraulic motor 2 may be a fixed displacement type motor.

[0017] Further, as described above, the test apparatus 1 includes a hydraulic pump 6 as a hydraulic pump that supplies pressure oil to the hydraulic motor 2, an electric motor 7 that drives the hydraulic pump 6, a direction switching valve 8 that switches the direction of the pressure oil discharged from the hydraulic pump 6 to supply it to the hydraulic motor 2, a pipeline 9 that circulates from the tank 10, passes through the hydraulic pump 6, the direction switching valve 8, and the hydraulic motor 2, and returns to the tank 10, and a controller 4 that controls the electric motor 7. In addition, it includes a load electric motor 3 that is connected to the rotating shaft 2a of the hydraulic motor 2 to be tested and can apply a load torque to the rotating shaft 2a of the hydraulic motor 2. Therefore, the hydraulic motor 2 can suck hydraulic oil from the tank 10 through the pipeline 9 and supply the pressure oil to the hydraulic motor 2 through the direction switching valve 8.

[0018] Subsequently, although not shown in the figure, the load electric motor 3 includes a stator and a rotor that can rotate around the axis with respect to the stator, and can output a torque that rotates the rotor around the axis by supplying current from the controller 4. The load electric motor 3 may be a brushless DC motor, a brushed motor, an induction motor, etc., as long as it can output a torque that rotates the rotor by current supply.

[0019] The output shaft 3a of the rotor of the load electric motor 3 is connected to the rotating shaft 2a via a speed reducer 5 that decelerates the rotational speed of the output shaft 3a and transmits it to the rotating shaft 2a of the hydraulic motor 2. Therefore, when the hydraulic motor 2 is rotationally driven, the rotational speed of the output shaft 3a is increased from the rotational speed of the rotating shaft 2a of the hydraulic motor 2 and rotates at a rotational speed obtained by multiplying the rotational speed of the rotating shaft 2a by the reciprocal of the reduction ratio.

[0020] As described above, the test apparatus 1 of this embodiment is equipped with a reduction gear 5. When current is supplied to the load electric motor 3, and a torque is output that drives the output shaft 3a in the opposite direction to the rotation direction of the rotation shaft 2a of the hydraulic motor 2, a torque equal to the reciprocal of the reduction ratio of that torque can be applied to the rotation shaft 2a of the hydraulic motor 2. Therefore, in the test apparatus 1 of this embodiment, by providing a reduction gear 5, a sufficiently large load torque can be applied to the rotation shaft 2a of the hydraulic motor 2 even with a small load electric motor 3 that has a small rated torque.

[0021] The hydraulic pump 6, acting as a hydraulic pump, is connected to the output shaft 7a of an electric motor 7, the drive shaft of which is controlled by a controller 4 (not shown in the figure). When rotationally driven by the electric motor 7, it can draw hydraulic fluid from the tank 8 and supply pressurized oil to the hydraulic motor 2. The hydraulic pump 6 may be a variable displacement pump or a fixed displacement pump, and may be a piston pump, vane pump, gear pump, etc.

[0022] The electric motor 7, although not shown in the diagram, comprises a stator and a rotor that is rotatable around the stator axis and connected to the drive shaft of the hydraulic pump 6. The controller 4 supplies current to rotate the rotor around its axis, thereby rotationally driving the hydraulic pump 6. The electric motor 7 only needs to be able to rotationally drive the hydraulic pump 6 connected to the output shaft 7a of the rotor by supplying current, so it can be a brushless DC motor, a brushed motor, an induction motor, etc.

[0023] The electric motor 7 is controlled by the controller 4 and rotates the hydraulic pump 6 from a stopped state. The hydraulic pump 6 supplies pressurized oil to the hydraulic motor 2, causing the hydraulic motor 2 to start rotating. From the time the hydraulic motor 2 starts rotating until the rotation speed of the rotating shaft 2a reaches the first test rotation speed, the electric motor 7 gradually increases its own rotation speed, thereby increasing the rotation speed of the hydraulic motor 2. The first test rotation speed is the rotation speed of the hydraulic motor 2 that is predetermined by the test conditions, which are the conditions under which the hydraulic motor 2 is tested.

[0024] On the other hand, after the rotational speed of the hydraulic motor 2 reaches the first test rotational speed, the electric motor 7 is driven at a predetermined rotational speed to maintain the rotational speed of the hydraulic motor 2 at the first test rotational speed during the test of the hydraulic motor 2, thereby rotating the hydraulic pump 6 at a constant rotational speed. Therefore, the hydraulic pump 6 supplies a predetermined constant flow rate of pressurized oil to the hydraulic motor 2 during the test of the hydraulic motor 2. The hydraulic motor 2 is equipped with a hydraulic cylinder (not shown) that drives the swash plate, a passage that supplies and discharges a portion of the pressurized oil supplied from the hydraulic pump 6 to the hydraulic cylinder, and a solenoid valve that opens and closes the passage, and the tilt angle of the swash plate can be changed by opening and closing the solenoid valve.

[0025] The directional control valve 8 is a three-position, three-port electromagnetic directional control valve with a neutral position that cuts off communication between the hydraulic pump 6 and the hydraulic motor 2, a first supply position that supplies pressurized oil from the hydraulic pump 6 to rotate the hydraulic motor 2 in the forward direction, and a second supply position that supplies pressurized oil from the hydraulic pump 6 to rotate the hydraulic motor 2 in the reverse direction, and is controlled by the controller 4.

[0026] As shown in Figure 2, the controller 4 comprises a pump control unit 4a that controls the hydraulic pump 6, a motor control unit 4b that controls the load electric motor 3, and an operation panel 4c that receives input of test conditions and instructions to start and stop the test. The controller 4 drives the hydraulic pump 6 at a predetermined rotational speed to supply a constant flow rate of pressurized oil from the hydraulic pump 6 to the hydraulic motor 2, while controlling the load electric motor 3 to apply load torque to the rotating shaft 2a of the hydraulic motor 2 according to the load pressure indicated by the predetermined test conditions.

[0027] The control panel 4c, although not shown in the illustration, is a touch panel and includes an area for displaying buttons for receiving input of test conditions, and an area for displaying start and stop buttons for the test. It accepts input of test conditions, and instructions to start and stop the test via touch operation by the user of the test device 1. Note that the control panel 4c is not limited to a touch panel, and may be configured to include an input device consisting of keys or buttons for receiving user operations, and a display device for displaying the input information, test conditions, and other data, either in place of or in addition to the touch panel.

[0028] The controller 4 is connected to one or more sensors (not shown) suitable for collecting test data, depending on the test data required to be collected during the test of the hydraulic motor 2. When the test of the hydraulic motor 2 is completed, the controller 4 processes the data collected by the sensors to obtain test results showing the performance of the hydraulic motor 2, and prints these results, along with the data collected during the test, onto paper using the printer 11. In addition to printing the test results and data to the printer 11, the controller 4 may also store the test results and data in a storage device (not shown) or transmit them to an external server or the like.

[0029] As shown in Figure 3, the pump control unit 4a includes a driver 4a1 that supplies current to the electric motor 7 and a signal generation unit 4a2 that outputs a PWM signal to the driver 4a1 according to the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 12, thereby rotating the electric motor 7 by providing the PWM signal to the driver 4a1.

[0030] In this embodiment, the driver 4a1 is a drive circuit that receives power from a power source (not shown) and supplies current to the electric motor 7. Although not shown, the driver 4a1 includes several switches that, when turned on, connect the electric motor 7 to the power source and supply current to the windings, and when turned off, disconnect the electric motor 7 windings from the power source and stop supplying current to the windings. When a PWM signal is input to the driver 4a1, it turns on the switches according to the duty cycle indicated by the PWM signal and supplies current to the electric motor 7.

[0031] When the test of the hydraulic motor 2 is started, the pump control unit 4a supplies current to the electric motor 7 to rotate the hydraulic pump 6. The pump control unit 4a gradually increases the rotational speed of the electric motor 7 until the rotational shaft 2a of the hydraulic motor 2 reaches the first test rotational speed indicated by the test conditions, thereby gradually increasing the discharge flow rate of pressurized oil from the hydraulic pump 6 over time. Furthermore, during the period from when the hydraulic motor 2 is started to rotate until the rotational speed of the hydraulic motor 2 reaches the first test rotational speed indicated by the test conditions, the pump control unit 4a decreases the rate at which the rotational speed of the hydraulic motor 2 is increased towards the end of the period. To achieve this, in the test apparatus 1 of this embodiment, the signal generation unit 4a3 monitors the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 12, determines the voltage to be supplied to the electric motor 7 according to the discharge flow rate of the hydraulic pump 6, and generates a PWM signal to be given to the driver 4a1 so that the said voltage can be applied to the electric motor 7.

[0032] Specifically, the signal generation unit 4a2 monitors the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 12. As shown in Figure 4, during the period from when the hydraulic pump 6 starts rotating until the target discharge flow rate is reached, the rate of increase of the rotational speed of the electric motor 7 is increased from the time the hydraulic motor 2 starts rotating until the rotational speed of the hydraulic motor 2 approaches the first test rotational speed, and a PWM signal is generated to decrease the rate of increase of the rotational speed of the electric motor 7 towards the end of the period. Here, the target discharge flow rate is set to the discharge flow rate discharged by the hydraulic pump 6 when the rotational speed of the hydraulic motor 2, which is supplied with pressurized oil from the hydraulic pump 6, reaches the first test rotational speed. Also, when the hydraulic pump 6 starts rotating, pressurized oil is supplied to the hydraulic motor 2, and the hydraulic motor 2 also starts rotating. The period from when the hydraulic pump 6 is started to when its discharge flow rate reaches the target discharge flow rate is short, provided that the length of the piping connecting the hydraulic pump 6 and the hydraulic motor 2 is not excessively long. Therefore, this period can be treated as coinciding with the period from when the hydraulic motor 2 is started to when its rotational speed reaches the first test rotational speed.

[0033] As described above, when the discharge flow rate of the hydraulic pump 6 is in the range below the flow rate threshold value set to 90% of the target flow rate, the signal generation unit 4a2 generates a PWM signal so as to increase the voltage applied to the electric motor 7 by a predetermined X volts every predetermined t1 seconds. When the discharge flow rate of the hydraulic pump 6 is in the range exceeding the flow rate threshold value, a PWM signal is generated so as to increase the voltage applied to the electric motor 7 by X volts every t2 seconds determined to be a value larger than t1. Note that the relationship is t1 < t2, and the rate of increase in the rotational speed of the electric motor 7 when the discharge flow rate of the hydraulic pump 6 is in the range below the flow rate threshold value is higher than the rate of increase in the rotational speed of the electric motor 7 when the discharge flow rate of the hydraulic pump 6 is in the range exceeding the flow rate threshold value. Thus, in the test apparatus 1 of the present embodiment, since the rotational speed of the hydraulic motor 2 is substantially proportional to the discharge flow rate of the hydraulic pump 6, the controller 4 monitors the discharge flow rate of the hydraulic pump 6 and changes the rate of increase in the rotational speed of the hydraulic motor 2 from the start of rotation until the rotational speed reaches the first test rotational speed based on the discharge flow rate of the hydraulic pump 6.

[0034] Then, when the discharge flow rate of the hydraulic pump 6 detected by the flow rate sensor 12 rises to the target discharge flow rate at which the rotation shaft 2a of the hydraulic motor 2 reaches the first test rotational speed, the signal generation unit 4a2 obtains the target voltage of the electric motor 7 so that the discharge flow rate of the hydraulic pump 6 becomes the target flow rate so that the rotation shaft 2a of the hydraulic motor 2 can be driven at the first test rotational speed, and generates a PWM signal so as to apply a voltage equal to the target voltage to the electric motor 7 and outputs it to the driver 4a1.

[0035] Therefore, the discharge flow rate of the hydraulic pump 6 increases at a high rate for a while after the rotating shaft 2a of the hydraulic motor 2 starts to rotate, and the rate of increase in rotational speed decreases before the rotational speed of the hydraulic motor 2 reaches the first test rotational speed. In this way, the rotational speed of the hydraulic motor 2 increases rapidly from the time the hydraulic motor 2 starts to rotate until it reaches a rotational speed slightly lower than the first test rotational speed, and then the increase in the rotational speed of the hydraulic motor 2 becomes gradual. This shortens the time required for the rotational speed of the hydraulic motor 2 to reach the first test rotational speed, and suppresses the rotational speed from overshooting the first test rotational speed. Furthermore, even if the rotational speed overshoots the first test rotational speed, the amount of overshoot is small and the amount of voltage manipulation is also small, thus suppressing the hunting of the rotational speed of the hydraulic motor 2 around the first test rotational speed.

[0036] In contrast, if the rate of increase of the rotational speed of the hydraulic motor 2 is set to be the same as the rate of increase when the rotational speed is below the flow rate threshold, and the rotational speed of the hydraulic motor 2 is brought up to the first test rotational speed, as shown by the dashed line in Figure 4, the rate of increase of the rotational speed of the hydraulic motor 2 is high, so the rotational speed of the hydraulic motor 2 greatly overshoots the first test rotational speed. In an attempt to return the rotational speed to the first test rotational speed, the motor 2 repeatedly hunts until the rotational speed converges to the first test rotational speed, resulting in a longer test preparation time, which is the time from when the hydraulic motor 2 starts rotating until the rotational speed stabilizes at the first test rotational speed for the test to be conducted. Furthermore, even if the rate of increase of the rotational speed of the hydraulic motor 2 is lowered to prevent hunting after the rotational speed of the hydraulic motor 2 reaches the first test rotational speed, as shown by the double-dashed line in Figure 4, the time it takes for the rotational speed of the hydraulic motor 2 to reach the first test rotational speed becomes longer, and thus the test preparation time also becomes longer. In contrast, in the test apparatus 1 of this embodiment, the rotational speed of the hydraulic motor 2 increases rapidly until it starts rotating and reaches a rotational speed slightly lower than the first test rotational speed. After that, the increase in the rotational speed of the hydraulic motor 2 becomes gradual. This shortens the time required for the rotational speed of the hydraulic motor 2 to reach the first test rotational speed, while suppressing the hunting of the rotational speed of the hydraulic motor 2 around the first test rotational speed. As a result, the test preparation time can be shortened, as shown in Figure 4.

[0037] As mentioned above, the signal generation unit 4a2 compares the discharge flow rate of the hydraulic pump 6 with a flow rate threshold set to 90% of the target flow rate. If the discharge flow rate is below the flow rate threshold, it generates a PWM signal to increase the voltage supplied to the electric motor 7 by a predetermined X volts every predetermined t1 seconds. If the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, it generates a PWM signal to increase the voltage supplied to the electric motor 7 by X volts every t2 seconds, which is set to a predetermined time longer than t1 seconds. In this way, when the discharge flow rate of the hydraulic pump 6 is below the flow rate threshold, the acceleration ratio of the hydraulic motor 2 increases, and when the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, the acceleration ratio of the hydraulic motor 2 decreases. Alternatively, the signal generation unit 4a2 may generate a PWM signal to increase the voltage supplied to the electric motor 7 by a predetermined X1 volt every predetermined t3 seconds when the discharge flow rate of the hydraulic pump 6 is below the flow rate threshold, and generate a PWM signal to increase the voltage supplied to the electric motor 7 by a value greater than X1, by X2 volts every t3 seconds when the discharge flow rate of the hydraulic pump 6 is above the flow rate threshold. Even in this case, the rate of increase of the rotational speed of the hydraulic motor 2 when the discharge flow rate of the hydraulic pump 6 is below the flow rate threshold will be higher than the rate of increase of the rotational speed of the hydraulic motor 2 when the discharge flow rate of the hydraulic pump 6 is above the flow rate threshold. Note that the control of the electric motor 7 from the time the hydraulic motor 2 starts rotating until it reaches the first test rotational speed indicated by the test conditions, insofar as the rate of increase of the rotational speed of the hydraulic motor 2 can be reduced at the end of the period, is not limited to the above example and can be modified in design.

[0038] Furthermore, although the pump control unit 4a changes the rate of increase of the rotational speed of the hydraulic motor 2 based on the discharge flow rate of the hydraulic pump 6, the rotational speed of the hydraulic motor 2 may be directly detected and the rate of increase may be changed based on the rotational speed of the hydraulic motor 2. If the pump control unit 4a directly detects the rotational speed of the hydraulic motor 2 and changes the rate of increase based on the rotational speed of the hydraulic motor 2, a threshold should be set for the rotational speed of the hydraulic motor 2. However, when detecting the rotational speed of the hydraulic motor 2, it becomes difficult to accurately control the electric motor 7 because it is easily affected by the efficiency and inertia of the hydraulic motor 2. Therefore, it is possible to control the hydraulic pump 6 more accurately by monitoring the discharge flow rate of the hydraulic pump 6 using the flow sensor 12 and managing the flow rate of the hydraulic pump 6, as this is less affected by the efficiency and inertia of the hydraulic motor 2.

[0039] Furthermore, the flow rate threshold may be set to a value other than 90% of the target flow rate, which is the discharge flow rate of the hydraulic pump 6 that allows the hydraulic motor 2 to rotate at the first test rotation speed indicated by the test conditions. Also, as shown in Figure 7, although the flow rate threshold is set to change the rate of increase of the rotation speed of the hydraulic motor 2, multiple flow rate thresholds may be set for the discharge flow rate, and the rate of increase may be changed multiple times between the time the hydraulic motor 2 starts rotating and the time it reaches the first test rotation speed. Therefore, for example, a first flow rate threshold set to a value smaller than the target flow rate, and a second flow rate threshold set to a value smaller than the target flow rate and larger than the first flow rate threshold may be set. If the acceleration factor of the hydraulic motor 2 in the range until the discharge flow rate of the hydraulic pump 6 reaches the first flow rate threshold is α, the acceleration factor of the hydraulic motor 2 in the range until the discharge flow rate of the hydraulic pump 6 exceeds the first flow rate threshold and reaches the second flow rate threshold is β, and the acceleration factor of the hydraulic motor 2 in the range until the discharge flow rate of the hydraulic pump 6 exceeds the second flow rate threshold and reaches the target flow rate is γ, then the acceleration factors may be set such that α > β > γ. In this way, the acceleration factor of the rotational speed of the hydraulic motor 2 decreases in stages, and as the rotational speed of the hydraulic motor 2 approaches the first test rotational speed, the acceleration factor can be reduced, thereby further suppressing the rotational speed of the hydraulic motor 2 from overshooting the first test rotational speed and suppressing hunting. Thus, when gradually reducing the rate of increase of the rotational speed of the hydraulic motor 2, any control method can be adopted for the control of the electric motor 7, as long as it is possible to gradually reduce the rate of increase of the rotational speed of the hydraulic motor 2.

[0040] Next, as shown in Figure 5, the motor control unit 4b includes a driver 4b1 that supplies current to the load electric motor 3, a torque control unit 4b2 that generates a current command that instructs the current to be supplied to the load electric motor 3 based on the rotational speed of the load electric motor 3 detected by the rotational speed sensor 13 and the torque indicated by the test conditions, and a current control unit 4b3 that generates a PWM signal to be given to the driver 4b1 based on the difference between the current indicated by the current command and the current flowing through the load electric motor 3 detected by the current sensor 14.

[0041] The rotational speed detection unit 13, although not shown in the figure, may be a rotary encoder or resolver that detects the rotational speed of the output shaft 3a of the load electric motor 3 relative to the stator 3b. Alternatively, it may be a sensor that detects the rotational position of the output shaft 3a relative to the stator 3b and detects the rotational speed of the output shaft 3a by differentiating or filtering the rotational position.

[0042] The current sensor 14 detects the current flowing through the windings of the load electric motor 3 (not shown). The current sensor 14 may be installed inside the load electric motor 3, or it may be installed in the wiring connected to the windings of the driver 4b1, which will be described later.

[0043] In this embodiment, the driver 4b1 is a drive circuit that receives power from a power source (not shown) and supplies current to the load electric motor 3. Although not shown, the driver 4b1 has multiple switches that, when turned on, connect the load electric motor 3 to the power source and supply current to the windings, and when turned off, disconnect the connection between the windings of the load electric motor 3 and the power source and stop supplying current to the windings. When a PWM signal is input to the driver 4b1, it turns on the switches according to the duty cycle indicated by the PWM signal and supplies current to the load electric motor 3.

[0044] The torque control unit 4b2 determines the torque required for the load electric motor 3, determines the target current necessary for the load electric motor 3 to output that torque, and generates a current command indicating that target current. During the test of the hydraulic motor 2, the torque control unit 4b2 controls the load electric motor 3 so that it applies a load torque corresponding to the load pressure indicated by the test conditions of the hydraulic motor 2 in the opposite direction to the rotation of the rotation shaft 2a of the hydraulic motor 2, that is, in a direction that brakes the rotation of the rotation shaft 2a.

[0045] The test conditions for the hydraulic motor 2 are input to the controller 4 in advance prior to the test of the hydraulic motor 2. The torque control unit 4b2 monitors the rotational speed of the load electric motor 3 and determines the current required for the load electric motor 3 to output a load torque corresponding to the load pressure indicated by the test conditions at the current rotational speed of the load electric motor 3.

[0046] Since the characteristics of the load electric motor 3 used in the test apparatus 1 are known from the specifications of the load electric motor 3, the torque control unit 4b2 can determine the current to be supplied to the load electric motor 3 from the rotational speed of the load electric motor 3 and the load torque corresponding to the load pressure indicated by the test conditions. In this embodiment, since the test apparatus 1 is equipped with a reduction gear 5, the torque control unit 4b2 can determine the torque that the load electric motor 3 should output from the load torque to be applied to the rotating shaft 2a of the hydraulic motor 2 indicated by the test conditions and the reduction ratio of the reduction gear 5, and then determine the current command from that torque and the current rotational speed of the output shaft 3a. If the torque indicated by the test conditions represents the torque of the load electric motor 3 taking into account the reduction ratio of the reduction gear 5, the torque control unit 4b2 can determine the current command from the torque indicated by the test conditions and the rotational speed of the output shaft 3a.

[0047] The hydraulic motor 2 is tested after the hydraulic pump 6 supplies pressurized oil to the hydraulic motor 2, the hydraulic motor 2 starts rotating, the rotation speed of the hydraulic motor 2's rotating shaft 2a reaches the first test rotation speed, and stabilizes at the first test rotation speed. When the rotation speed of the hydraulic motor 2's rotating shaft 2a reaches the first test rotation speed and the hydraulic motor 2 is ready for testing, the torque control unit 4b2 requests a current command to apply a load torque corresponding to the load pressure indicated by the test conditions to the rotating shaft 2a of the hydraulic motor 2 in the opposite direction to the rotation direction of the rotating shaft 2a.

[0048] On the other hand, during the test preparation time from when the hydraulic motor 2 is started to when its rotational speed reaches and stabilizes at the first test rotational speed, the torque control unit 4b2 requests a current command to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 by driving the output shaft 3a of the load electric motor 3 to apply torque in a direction that matches the rotational direction of the rotational shaft 2a of the hydraulic motor 2 when starting the rotational speed of the rotational shaft 2a of the hydraulic motor 2. The controller 4 may continue to drive the load electric motor 3 to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 until the rotational speed of the rotational shaft 2a of the hydraulic motor 2 reaches the first test rotational speed. Alternatively, the controller 4 may use an assist stop rotational speed lower than the first test rotational speed as a threshold and continue to drive the load electric motor 3 to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 until the rotational speed of the rotational shaft 2a of the hydraulic motor 2 reaches the assist stop rotational speed. Furthermore, the controller 4 may also drive the load motor 3 only during the period from when it starts supplying pressurized oil from the hydraulic pump 6 to the hydraulic motor 2 until the rotating shaft 2a of the hydraulic motor 2 starts to rotate, thereby assisting the rotation of the rotating shaft 2a.

[0049] Thus, when the rotating shaft 2a of the hydraulic motor 2 is started to rotate, the torque control unit 4b2 requests a current command to cause the load electric motor 3 to output a torque that assists in the rotation of the rotating shaft 2a. Then, when the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches a predetermined first test rotational speed and preparations for conducting the test are complete and test data can be collected, the torque control unit 4b2 requests a current command to cause the load electric motor 3 to apply a load torque in a direction that suppresses the rotation of the rotating shaft 2a of the hydraulic motor 2.

[0050] Furthermore, even when the capacity of the hydraulic motor 2 is reduced to increase the rotational speed of the rotating shaft 2a, the torque control unit 4b2 requests a current command to cause the load electric motor 3 to output an assist torque to help start the rotation of the rotating shaft 2a.

[0051] The current control unit 4b3 receives feedback of the current detected by the current sensor 14, calculates the difference between the current instructed by the current command and the current detected by the current sensor 14, compensates for this difference proportionally and integrally or proportionally, differentially and integrally to determine the current to be supplied to the load electric motor 3, generates a PWM signal to drive the switch of the driver 4b1 to realize the current to be supplied to the load electric motor 3, and outputs the PWM signal to the driver 4b1.

[0052] The torque control unit 4b2 generates a current command to apply the torque output by the load electric motor 3 to the rotating shaft 2a in a direction that assists the rotation of the rotating shaft 2a when starting the rotation of the hydraulic motor 2. When the rotational speed of the rotating shaft 2a reaches the first test rotational speed, the torque control unit 4b2 generates a current command to stop the load electric motor 3 from assisting the rotation of the rotating shaft 2a and not apply torque to the rotating shaft 2a. When the rotational speed of the rotating shaft 2a stabilizes and the conditions for starting the test are met and test data is to be collected, the torque output by the load electric motor 3 is generated as a load torque that hinders the rotation of the rotating shaft 2a. Furthermore, even when the capacity of the hydraulic motor 2 is reduced during the test of the hydraulic motor 2 to increase the rotational speed of the rotating shaft 2a, the torque control unit 4b2 generates a current command to apply the torque output by the load electric motor 3 to the rotating shaft 2a in a direction that assists the rotation of the rotating shaft 2a.

[0053] The torque control unit 4b2 monitors the rotational speed of the load electric motor 3, and from the rotational speed of the load electric motor 3, it determines the rotational speed of the rotating shaft 2a of the hydraulic motor 2 and decides whether to direct the torque output by the load electric motor 3 to assist or inhibit the rotation of the rotating shaft 2a. Alternatively, the torque control unit 4b2 may detect the discharge flow rate of the hydraulic pump 6 and estimate the rotational speed of the rotating shaft 2a of the hydraulic motor 2. Furthermore, during testing of the hydraulic motor 2, when the capacity of the hydraulic motor 2 is reduced and the load electric motor 3 is to output assist torque, the torque control unit 4b2 receives a signal to drive a solenoid valve to reduce the tilt angle of the swash plate (not shown) of the hydraulic motor 2. Using this signal as a trigger, the torque control unit 4b2 outputs a current command to generate assist torque from the load electric motor 3 to assist the rotation of the rotating shaft 2a.

[0054] Furthermore, when the hydraulic pump 6 discharges a predetermined flow rate, the torque control unit 4b2 sets the rotational speed of the rotating shaft 2a of the hydraulic motor 2, which has a reduced capacity, as the second test rotational speed. When the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches the second test rotational speed, the torque control unit 4b2 stops applying assist torque from the load electric motor 3 to the rotating shaft 2a. Then, when collecting test data while the rotating shaft 2a is being driven at the second test rotational speed, the torque control unit 4b2 generates a current command so that the torque output by the load electric motor 3 acts on the rotating shaft 2a as a load torque that hinders the rotation of the rotating shaft 2a.

[0055] Although not shown in the hardware diagram, the controller 4 is configured to perform the calculations necessary for driving the load electric motor 3 and electric motor 7 in the pump control unit 4a and motor control unit 4b, and includes a CPU (Central Processing Unit) or similar processing unit, memory, an interface, and a bus that enables communication with each of the aforementioned devices. The pump control unit 4a and motor control unit 4b in the controller 4 are realized when the processing unit in the controller 4 executes a program for processing the operating system, pump control unit 4a, and motor control unit 4b. If the data collected by the flow sensor 12 and current sensor 14 can be used as test data, the flow sensor 12 and current sensor 14 may be used as sensors 4d for collecting test data.

[0056] Controller 4 is configured as described above, and the processes in Controller 4 will be explained below based on the flowchart shown in Figure 6. When the test start button on the control panel 4c is pressed down, Controller 4 drives the electric motor 7 to supply pressurized oil from the hydraulic pump 6 to the hydraulic motor 2 in order to start the test and start the rotation of the rotating shaft 2a of the hydraulic motor 2 (step S1). In addition, Controller 4 drives the load electric motor 3 to apply assist torque in a direction that assists the rotation of the rotating shaft 2a.

[0057] Furthermore, the controller 4 increases the voltage applied to the electric motor 7 by X volts to increase the rotational speed of the hydraulic motor 2 at a constant rate, thereby increasing the flow rate of the hydraulic pump 6 (step S2). Then, the controller 4 counts the time and waits for t1 seconds to elapse (step S3), compares the discharge flow rate of the hydraulic pump 6 with the flow rate threshold, and determines whether the discharge flow rate of the hydraulic pump 6 is below the flow rate threshold (step S4).

[0058] If the result of the determination in step S4 is that the discharge flow rate of the hydraulic pump 6 is below the flow rate threshold, the process returns to step S2, and a voltage X volts higher than the voltage applied to the electric motor 7 in the previous step is applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 (step S2).

[0059] On the other hand, if the result of the determination in step S3 indicates that the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, the controller 4 applies a voltage to the electric motor 7 that is X volts higher than the voltage applied to the electric motor 7 in the previous step to increase the flow rate of the hydraulic pump 6 (step S5), and the controller 4 counts the time and waits for t2 seconds, which is set to be longer than t1 seconds, to elapse (step S6).

[0060] Furthermore, the controller 4 compares the discharge flow rate of the hydraulic pump 6 with the target discharge flow rate and determines whether the discharge flow rate of the hydraulic pump 6 is less than or equal to the target flow rate (step S7).

[0061] If the result of the determination in step S7 is that the discharge flow rate of the hydraulic pump 6 is less than or equal to the target discharge flow rate, the controller 4 applies a voltage to the electric motor 7 that is X volts higher than the voltage previously applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 (step S5), and then counts the time and waits for t2 seconds to elapse (step S6). In this way, if the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, the controller 4 increases the voltage by X volts every t2 seconds, which is longer than t1 seconds, in the processing of steps S5 and S6. Therefore, when the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, the rate at which the rotational speed of the hydraulic motor 2 increases decreases.

[0062] On the other hand, if the result of the determination in step S7 indicates that the discharge flow rate of the hydraulic pump 6 exceeds the target discharge flow rate, the controller 4 controls the electric motor 7 by feeding back the discharge flow rate so that the discharge flow rate of the hydraulic pump 6 becomes the target discharge flow rate (step S8).

[0063] Thus, during the period from when the hydraulic motor 2 is started to rotate until the rotational speed of the hydraulic motor 2 reaches the first test rotational speed indicated by the test conditions, the controller 4 reduces the rate of increase of the hydraulic motor 2 towards the end of the period.

[0064] Therefore, in the test apparatus 1, the time required for the rotational speed of the hydraulic motor 2 to become slightly lower than the first test rotational speed is shortened, and thereafter, the rate of increase in the rotational speed of the hydraulic motor 2 is reduced, thereby suppressing the rotational speed of the hydraulic motor 2 from overshooting the first test rotational speed. Furthermore, even if the rotational speed overshoots the first test rotational speed, the amount of overshoot is small and the amount of voltage manipulation is also small, thus suppressing the hunting of the rotational speed of the hydraulic motor 2 around the first test rotational speed.

[0065] Furthermore, when a signal is input to the solenoid valve during the test to reduce the capacity of the hydraulic motor 2, the controller 4 uses the input of this signal as a trigger to drive the load electric motor 3 to apply an assist torque to the rotation axis 2a of the hydraulic motor 2 that matches the direction of rotation.

[0066] The controller 4 then continues to apply assist torque from the load electric motor 3 to the rotating shaft 2a, while monitoring the rotational speed of the hydraulic motor 2's rotating shaft 2a. When the rotational speed of the rotating shaft 2a reaches the second test rotational speed, the controller 4 stops the output of assist torque from the load electric motor 3, so that the rotating shaft 2a rotates without load and no torque is applied to the rotating shaft 2a.

[0067] When the rotational speed of the rotating shaft 2a stabilizes at the second test rotational speed, the controller 4 drives the load electric motor 3 to apply a load torque corresponding to the load pressure indicated by the test conditions to the rotating shaft 2a, thereby applying a load torque in the opposite direction to the rotational direction to the rotating shaft 2a of the hydraulic motor 2, and tests the hydraulic motor 2 to collect test data.

[0068] Furthermore, as shown in Figure 7, if multiple flow rate thresholds are set for the discharge flow rate, and the rate of increase is changed multiple times between the time the hydraulic motor 2 starts rotating and the time the rotational speed reaches the first test rotational speed, the controller 4 can process the data according to, for example, the flowchart shown in Figure 8. When the test start button on the control panel 4c is pressed down, the controller 4 drives the electric motor 7 to supply pressurized oil from the hydraulic pump 6 to the hydraulic motor 2 in order to start the test and start the rotation of the rotating shaft 2a of the hydraulic motor 2 (step S11). The controller 4 starts the rotation of the hydraulic motor 2 and drives the load electric motor 3 to apply assist torque in the direction that assists the rotation of the rotating shaft 2a.

[0069] Furthermore, the controller 4 increases the voltage applied to the electric motor 7 by X volts to increase the rotational speed of the hydraulic motor 2 at a constant rate, and increases the flow rate of the hydraulic pump 6 by Q1 (step S12). Then, the controller 4 counts the time and waits for t1 seconds to elapse (step S13), compares the discharge flow rate of the hydraulic pump 6 with the first flow rate threshold, and determines whether the discharge flow rate of the hydraulic pump 6 is less than or equal to the first flow rate threshold (step S14).

[0070] If the result of the determination in step S14 is that the discharge flow rate of the hydraulic pump 6 is below the first flow rate threshold, the process returns to step S12, and a voltage X volts higher than the voltage applied to the electric motor 7 last time is applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 by Q1 (step S12).

[0071] On the other hand, if the result of the determination in step S14 indicates that the discharge flow rate of the hydraulic pump 6 exceeds the first flow rate threshold, the controller 4 applies a voltage to the electric motor 7 that is X / 2 volts higher than the voltage previously applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 by Q1 / 2 (step S15). The controller 4 then counts the time and waits for t1 seconds to elapse (step S16), compares the discharge flow rate of the hydraulic pump 6 with the first flow rate threshold, and determines whether the discharge flow rate of the hydraulic pump 6 is less than or equal to the second flow rate threshold (step S17). The second flow rate threshold is set to a value greater than the first flow rate threshold and less than the target flow rate.

[0072] If, as a result of the determination in step S17, the discharge flow rate of the hydraulic pump 6 is less than or equal to the second flow rate threshold, a voltage X volts higher than the voltage previously applied to the electric motor 7 is applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 by Q1 (step S18). The controller 4 then counts the time and waits for t1 seconds to elapse (step S19), compares the discharge flow rate of the hydraulic pump 6 with the second flow rate threshold, and determines whether or not the discharge flow rate of the hydraulic pump 6 is less than or equal to the second flow rate threshold (step S20).

[0073] If the result of the judgment in step S20 is that the discharge flow rate of the hydraulic pump 6 is below the second flow rate threshold, the process returns to step S15, and a voltage X / 2 volts higher than the voltage previously applied to the electric motor 7 is applied to the electric motor 7 to increase the flow rate of the hydraulic pump 6 by Q1 / 2 (step S15). When the controller 4 performs the processes from step 15 to step 19, if the discharge flow rate of the hydraulic pump 6 is below the second flow rate threshold, the voltage of the electric motor 7 increases by 1.5 × X volts every 2 × t1 seconds. If the discharge flow rate of the hydraulic pump 6 is below the first flow rate threshold, the voltage of the electric motor 7 increases by X volts every t1 seconds, whereas if the discharge flow rate of the hydraulic pump 6 exceeds the first flow rate threshold but is below the second flow rate threshold, the voltage of the electric motor 7 increases by an average of 0.75 × X volts every t1 seconds. Therefore, when the discharge flow rate of the hydraulic pump 6 exceeds the first flow rate threshold but is less than or equal to the second flow rate threshold, the degree of increase in the rotational speed of the hydraulic motor 2 is less than the degree of increase in the rotational speed of the hydraulic motor 2 when the discharge flow rate of the hydraulic pump 6 is less than or equal to the first flow rate threshold.

[0074] Furthermore, if the voltage resolution that the controller 4 can apply to the electric motor 7 in the system is high, the voltage may be increased by 0.75 × X volts every t1 seconds in steps S15 and S16, and steps S18 to S20 may be omitted. If the discharge flow rate of the hydraulic pump 6 is below the second flow rate threshold determined in step 17, the process may return to step S15. In other words, if the voltage resolution that the controller 4 can apply to the electric motor 7 in the system is low, the process of increasing the voltage by 0.75 × X volts every t1 seconds can be simulated by dividing the process into steps 15 and 16 and steps 19 and 20. This allows for the use of a low-cost microcontroller and reduces the cost of the test device 1.

[0075] On the other hand, if the discharge flow rate of the hydraulic pump 6 exceeds the second flow rate threshold as determined in steps S17 and S20, the controller 4 applies a voltage to the electric motor 7 that is X volts higher than the voltage previously applied to the electric motor 7, increasing the flow rate of the hydraulic pump 6 by Q1 (step S21), and the controller 4 counts the time and waits for t2 seconds to elapse (step 22). Note that the value of t2 is set so that the value of X / t2 is smaller than the value of 0.75X / t1. Therefore, when the discharge flow rate of the hydraulic pump 6 exceeds the second flow rate threshold, the rate at which the rotational speed of the hydraulic motor 2 increases is reduced compared to when the processing from steps S15 to S19 is executed.

[0076] Furthermore, the controller 4 compares the discharge flow rate of the hydraulic pump 6 with the target discharge flow rate and determines whether the discharge flow rate of the hydraulic pump 6 is less than or equal to the target discharge flow rate (step S23). If the result of the determination in step S23 is that the discharge flow rate of the hydraulic pump 6 is less than or equal to the target discharge flow rate, the controller 4 returns to the process in step S21.

[0077] On the other hand, if the result of the determination in step S23 indicates that the discharge flow rate of the hydraulic pump 6 exceeds the target discharge flow rate, the controller 4 controls the electric motor 7 by feeding back the discharge flow rate so that the discharge flow rate of the hydraulic pump 6 becomes the target discharge flow rate (step S24).

[0078] Thus, during the period from when the hydraulic motor 2 is started to rotate until the rotational speed of the hydraulic motor 2 reaches the first test rotational speed indicated by the test conditions, the controller 4 gradually reduces the rate of increase of the hydraulic motor 2 towards the end of the period.

[0079] Therefore, in the test apparatus 1, the time required for the rotational speed of the hydraulic motor 2 to become slightly lower than the first test rotational speed is shortened, and thereafter, the rate of increase in the rotational speed of the hydraulic motor 2 is reduced, thereby suppressing the rotational speed of the hydraulic motor 2 from overshooting the first test rotational speed. Furthermore, even if the rotational speed overshoots the first test rotational speed, the amount of overshoot is small and the amount of voltage manipulation is also small, thus suppressing the hunting of the rotational speed of the hydraulic motor 2 around the first test rotational speed.

[0080] As described above, the test apparatus 1 of this embodiment is a test apparatus 1 capable of applying a load torque in the opposite direction to the rotation direction of the hydraulic motor 2 to the rotating shaft 2a of the hydraulic motor 2, and comprises a hydraulic pump (hydraulic pump) 6 that supplies working fluid to the hydraulic motor 2, an electric motor 7 that drives the hydraulic pump (hydraulic pump) 6, and a controller 4 that controls the electric motor 7, and the controller 4 reduces the rate of increase of the rotation speed of the hydraulic motor 2 at the end of the period from when the hydraulic motor 2 is started to rotate until the rotation speed of the hydraulic motor 2 reaches the first test rotation speed (test rotation speed) indicated by the test conditions.

[0081] With the test apparatus 1 configured in this way, the rate of increase is reduced towards the end of the period from when the hydraulic motor 2 is started to when the rotational speed of the hydraulic motor 2 reaches the test rotational speed indicated by the test conditions. This increases the rate of increase of the rotational speed of the hydraulic motor 2, shortening the time required for the rotational speed of the hydraulic motor 2 to rise to near the test rotational speed. Subsequently, by reducing the rate of increase of the rotational speed of the hydraulic motor 2, it is possible to suppress the rotational speed of the hydraulic motor 2 from overshooting the first test rotational speed. Even if the rotational speed overshoots the first test rotational speed, the amount of overshoot is reduced, thus suppressing hunting, where the rotational speed of the hydraulic motor 2 becomes oscillating around the test rotational speed. Therefore, with the test apparatus 1 of this embodiment, the time required for the rotational speed of the hydraulic motor 2 to rise to near the test rotational speed can be shortened and hunting can be suppressed, thus shortening the test preparation time from when the hydraulic motor 2 is started until the rotational speed of the hydraulic motor 2 stabilizes at the test rotational speed and the test can be performed.

[0082] Furthermore, the test apparatus 1 can also gradually decrease the rate of increase of the rotational speed of the hydraulic motor 2. When the test apparatus 1 gradually decreases the rate of increase of the rotational speed of the hydraulic motor 2 in this way, even if the rate of increase of the hydraulic motor 2 is increased further until the rotational speed of the hydraulic motor 2 rises close to the first test rotational speed (test rotational speed), the rate of increase can be gradually reduced as the rotational speed of the hydraulic motor 2 approaches the first test rotational speed (test rotational speed). This suppresses hunting of the rotational speed of the hydraulic motor 2, and thus further shortens the test preparation time.

[0083] Furthermore, the test apparatus 1 of this embodiment is equipped with a flow sensor 12 that detects the flow rate of pressurized oil (working fluid) supplied from the hydraulic pump 6 to the hydraulic motor 2. The controller 4 monitors the flow rate of pressurized oil (working fluid) detected by the flow sensor 12 and controls the rotational speed of the electric motor 7 to adjust the rate of increase of the hydraulic motor 2. With the test apparatus 1 configured in this way, compared to directly detecting the rotational speed of the hydraulic motor 2, the flow rate of the hydraulic pump 6 can be monitored and managed by using the flow sensor 12, which is not affected by the efficiency or inertia of the hydraulic motor 2. As a result, the hydraulic pump 6 can be controlled with high precision, and the test preparation time can be easily shortened.

[0084] Furthermore, the test apparatus 1 of this embodiment includes a load electric motor 3 connected to the rotating shaft 2a of the hydraulic motor 2 and capable of applying load torque to the rotating shaft 2a of the hydraulic motor 2, and a controller 4 that controls the load electric motor 3. The controller 4 drives the load electric motor 3 to apply assist torque to the rotating shaft 2a of the hydraulic motor 2 when the hydraulic motor 2 starts rotating, thereby assisting the rotation of the hydraulic motor 2.

[0085] With the test apparatus 1 configured in this way, even when testing a hydraulic motor 2 that has a small output torque and cannot be started by simply supplying pressurized oil to the hydraulic motor 2 during rotational startup due to the inertial mass of the load electric motor 3 and the resistance of static friction, the hydraulic motor 2 can be started by adding an assist torque to the rotation shaft 2a of the hydraulic motor 2 to assist in the rotation of the hydraulic motor 2 during rotational startup.

[0086] Therefore, according to the test apparatus 1 of this embodiment, even if a large load motor 3 is installed to enable testing of large hydraulic motors with high output, it is also possible to test small hydraulic motors 2 with low output without difficulty. As described above, according to the test apparatus 1 of this embodiment, it is possible to smoothly test multiple hydraulic motors 2 with different outputs, and a wide range of hydraulic motors 2 can be tested with a single test apparatus 1.

[0087] Furthermore, in the test apparatus 1 of this embodiment, the hydraulic motor 2 is a variable displacement motor whose rotational speed can be changed by changing its capacity, and the controller 4 controls the load electric motor 3 to output assist torque when the capacity of the hydraulic motor 2 is reduced. When the capacity of the hydraulic motor 2 is reduced, the rotational speed of the hydraulic motor 2's shaft 2a increases. However, when the rotational speed of the shaft 2a increases, the output torque of the hydraulic motor 2 decreases, and the inertial mass of the load electric motor 3 acts on the rotational speed of the shaft 2a. In conventional test apparatuses, if the hydraulic motor 2 has a small output torque, the torque becomes insufficient, the rotational speed decreases, it may take time to recover the rotational speed, or the test may not be able to continue due to deviation from the test conditions. In contrast, with the test apparatus 1 of this embodiment, when the capacity of the hydraulic motor 2 is reduced, the load electric motor 3 is output assist torque, so even if the hydraulic motor 2 is small with a small output torque, the rotational speed of the shaft 2a can be quickly increased and raised to the second test rotational speed indicated by the test conditions. As described above, according to the test apparatus 1 of this embodiment, when increasing the rotational speed of the rotating shaft 2a, the load electric motor 3 assists in reducing the inertial force, allowing for smooth testing. In the test apparatus 1 of this embodiment, the load electric motor 3 outputs assist torque to help the rotation of the hydraulic motor 2 when starting the hydraulic motor 2 or when reducing its capacity, but this assistance does not need to be provided if it is not necessary.

[0088] Furthermore, the test apparatus 1 of this embodiment is equipped with a reduction gear 5 between the load electric motor 3 and the rotating shaft 2a, which reduces the rotational speed of the load electric motor 3 and transmits it to the rotating shaft 2a. With the test apparatus 1 configured in this way, even if a small load electric motor 3 is used via the reduction gear 5, sufficient load torque can be applied to the large hydraulic motor 2. Thus, it is possible to test a wide range of hydraulic motors 2 with a single test apparatus 1 while also achieving miniaturization and cost reduction.

[0089] This concludes the description of embodiments of the present invention, but the scope of the present invention is not limited to the details shown or described. [Explanation of symbols]

[0090] 1...Testing equipment, 2...Hydraulic motor, 4...Controller, 4a2...Flow sensor, 6...Hydraulic pump (hydraulic pump), 7...Electric motor

Claims

1. A test apparatus capable of applying a load torque to the rotating shaft of a hydraulic motor in the opposite direction to the rotation direction of the hydraulic motor, A hydraulic pump that supplies working fluid to the hydraulic motor, An electric motor that drives the aforementioned hydraulic pump, The system includes a controller that controls the aforementioned electric motor, The controller reduces the rate of increase in the rotational speed of the hydraulic motor at the end of the period from when the hydraulic motor is started to when the rotational speed of the hydraulic motor reaches the test rotational speed indicated by the test conditions. A test apparatus characterized by the following features.

2. The rate at which the rotational speed of the hydraulic motor is increased is gradually reduced. The test apparatus according to feature 1.

3. The system includes a flow sensor for detecting the flow rate of the working fluid supplied from the hydraulic pump to the hydraulic motor, The aforementioned controller, The flow rate of the working fluid detected by the flow sensor is monitored, and the rotation speed of the electric motor is controlled accordingly to adjust the rate of increase of the hydraulic motor. The test apparatus according to claim 1 or 2.

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