Test equipment

Abstract

The present invention provides a test apparatus that can prevent excessive pressure from occurring inside a hydraulic motor. [Solution] The test apparatus 1 of the present invention comprises a hydraulic pump 6 that supplies working fluid to a hydraulic motor 2 to rotate the hydraulic motor 2, a load electric motor 3 connected to the rotating shaft 2a of the hydraulic motor 2 and capable of applying a load torque to the rotating shaft 2a in the opposite direction to the rotation direction of the hydraulic motor 2, a rotation speed sensor 13 capable of detecting the rotation speed of the hydraulic motor 2, and a braking means B that reduces the rotation speed of the hydraulic motor 2 when the theoretical rotation speed Rt obtained by the rotation speed sensor 13 from the flow rate of the working fluid supplied to the hydraulic motor 2 exceeds the theoretical rotation speed Rt.

Description

Technical Field

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

Background Art

[0002] Conventional test devices for testing hydraulic motors connect an electric motor to the rotating shaft of the hydraulic motor via a coupling, supply a constant flow of pressurized oil from a hydraulic pump to the hydraulic motor to drive the hydraulic motor to rotate, and apply a load torque to the rotating shaft from the electric motor in the opposite direction to the rotation direction of the hydraulic motor, thereby creating an environment equivalent to the environment in which the hydraulic motor is actually used to test the performance of the hydraulic motor (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the output required for a hydraulic motor varies depending on the equipment used, a large number of hydraulic motors with different outputs are manufactured to suit the equipment used. However, if a separate test device is prepared for each hydraulic motor with a different output, it is uneconomical. Therefore, it is preferable that a single test device can test hydraulic motors with multiple different outputs.

[0005] When considering testing hydraulic motors with multiple different outputs using a test device, it is necessary to ensure that the electric motor can apply a load to a hydraulic motor with a large output. Therefore, it is required to use an electric motor that can handle the output of the hydraulic motors that can be tested by the test device.

[0006] Thus, in conventional testing equipment, it is necessary to employ an electric motor capable of applying a sufficiently large load torque to the hydraulic motor that exhibits the greatest output among the multiple hydraulic motors under test, which results in a large electric motor. When testing a small variable displacement hydraulic motor with low output among the hydraulic motors under test using such equipment, even if the hydraulic motor's capacity is increased during the test to reduce the speed, the rotational speed of the hydraulic motor does not decrease quickly due to the inertial force of the electric motor. This can cause the counterbalance valve installed in the hydraulic motor to shut off, resulting in excessive pressure inside the hydraulic motor.

[0007] Furthermore, even if the hydraulic motor is not of variable displacement type, when the test is completed and the rotational speed of the hydraulic motor is reduced, the rotational speed of the hydraulic motor may not be reduced quickly due to the inertial force of the electric motor, causing the counterbalance valve installed in the hydraulic motor to shut off, resulting in excessive pressure inside the hydraulic motor.

[0008] Therefore, the present invention aims to provide a test apparatus that can prevent the pressure inside a hydraulic motor from becoming excessive. [Means for solving the problem]

[0009] To achieve the above objectives, the test apparatus of the present invention comprises a hydraulic pump that supplies working fluid to a hydraulic motor to rotate it, a load electric motor connected to the rotating shaft of the hydraulic motor and capable of applying a load torque to the rotating shaft in the opposite direction to the rotation direction of the hydraulic motor, a rotation sensor capable of detecting the rotational speed of the hydraulic motor, and a braking means that determines the theoretical rotational speed from the flow rate of the working fluid supplied to the hydraulic motor and reduces the rotational speed of the hydraulic motor if the actual rotational speed of the hydraulic motor obtained by the rotational speed sensor exceeds the theoretical rotational speed.

[0010] With a test apparatus configured in this way, if the actual rotational speed of the hydraulic motor exceeds the theoretical rotational speed, the braking means will reduce the rotational speed of the hydraulic motor. This prevents the amount of working fluid required by the hydraulic motor from exceeding the discharge flow rate of the hydraulic pump, thereby preventing excessive pressure inside the hydraulic motor.

[0011] Furthermore, the braking means in the test apparatus may include a brake comprising: a friction plate connected to the rotating shaft of a hydraulic motor; a friction member positioned spaced apart from the friction plate and movable relative to the friction plate, which, when in contact with the friction plate, suppresses the rotation of the hydraulic motor; a cylinder provided with a pressure chamber capable of pressing the friction member against the friction plate; and a pressure regulating valve for adjusting the pressure supplied to the pressure chamber.

[0012] With this test apparatus configured, the braking force applied by the brake to the rotating shaft of the hydraulic motor can be adjusted by the pressure control valve. Furthermore, with this test apparatus, the rotational speed of the hydraulic motor can be quickly adjusted to match the discharge flow rate of the hydraulic pump by appropriately adjusting the braking force of the brake.

[0013] Furthermore, the braking mechanism in the test apparatus may reduce the rotational speed of the hydraulic motor if the actual rotational speed exceeds the value obtained by multiplying the theoretical rotational speed by a safety factor. With a test apparatus configured in this way, by appropriately using a safety factor suitable for the test preparation time, a safety factor suitable for reducing the rotational speed of the hydraulic motor by increasing the capacity of the hydraulic motor, and a safety factor suitable for the stopping process time, the rotational speed of the hydraulic motor can be appropriately reduced, and the excessive pressure inside the hydraulic motor can be further suppressed.

[0014] Furthermore, the test apparatus may reduce the rotational speed of the hydraulic motor by outputting torque from the load electric motor in the opposite direction to the rotational direction of the hydraulic motor's rotation axis. With a test apparatus configured in this way, the rotational speed of the hydraulic motor is reduced using the load electric motor, so there is no need to provide a mechanical brake, which reduces costs.

[0015] Furthermore, the hydraulic motor is a variable displacement type hydraulic motor, and the braking means in the test apparatus may decelerate the rotational speed of the hydraulic motor when the hydraulic motor increases its displacement. According to the test apparatus configured as described above, in a situation where the displacement of the hydraulic motor is increased and the rotational speed of the hydraulic motor decreases, even when it is difficult for the rotational speed of the hydraulic motor to decrease due to the inertia of the load electric motor, the brake is operated to quickly decrease the rotational speed of the rotating shaft of the hydraulic motor, thereby preventing the pressure in the hydraulic motor from becoming excessive.

Advantages of the Invention

[0016] The test apparatus of the present invention can prevent the pressure in the hydraulic motor from becoming excessive.

Brief Description of the Drawings

[0017] [Figure 1] It is a configuration diagram of a test apparatus in one embodiment. [Figure 2] It is a circuit diagram of a hydraulic motor. [Figure 3] It is a circuit diagram of a brake. [Figure 4] It is a configuration diagram of a controller of a test apparatus in one embodiment. [Figure 5] It is a configuration diagram of a pump control unit in a controller. [Figure 6] It is a configuration diagram of a motor control unit in a controller. [Figure 7] It is a configuration diagram of a brake control unit in a controller. [Figure 8] It is a flowchart showing a processing procedure related to the control of a load electric motor in a controller of a test apparatus according to one embodiment. [Figure 9] It is a flowchart showing a processing procedure related to the control of a brake in a controller of a test apparatus according to one embodiment.

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, a test apparatus 1 in one embodiment includes a hydraulic pump 6 as a hydraulic pump that supplies pressure oil as a working fluid to a hydraulic motor 2 that is a test object, and is connected to a rotating shaft 2a of the hydraulic motor 2 and can apply a load torque in the opposite direction to the rotation direction of the hydraulic motor 2 to the rotating shaft 2a. A load electric motor 3 as an electric motor, and braking means B for decelerating the rotation speed of the hydraulic motor 2 based on the theoretical rotation speed Rt obtained from the flow rate of the pressure oil supplied to the hydraulic motor 2 and the actual rotation speed Ra of the hydraulic motor 2.

[0019] Further, the test apparatus 1 includes a pump electric motor 7 that drives a hydraulic pump 6 as a hydraulic pump that supplies pressure oil to the hydraulic motor 2, a direction switching valve 8 that switches the direction of supplying the pressure oil discharged from the hydraulic pump 6 to the hydraulic motor 2, and a hydraulic motor 2. A brake 20 capable of decelerating the rotation speed of the load electric motor 3, a pump electric motor 7, and a controller 4 that controls the brake 20. In the present embodiment, the brake 20 and the controller 4 constitute the braking means B.

[0020] Hereinafter, each part of the test apparatus 1 will be described. First, the hydraulic motor 2 that is the test object of the test apparatus 1 will be described. In the present embodiment, the hydraulic motor 2 includes a rotating shaft 2a for transmitting power to the outside, and is a variable displacement type hydraulic piston motor using the working fluid as hydraulic oil. Although not shown, it includes a swash plate, a cylinder that drives the swash plate, and a solenoid valve for controlling the expansion and contraction of the cylinder. By changing the tilt angle of the swash plate, the capacity can be changed, and the rotation speed can be changed even if the amount of working oil is constant.

[0021] Note that the hydraulic motor 2 may be driven using a liquid other than hydraulic oil as the working fluid. When it is a variable displacement type, in addition to a piston motor, it may be a vane motor in which the capacity can be changed by adjusting the eccentricity of the cam ring with respect to the rotor. Further, since the test apparatus 1 can also be used for testing a fixed displacement type hydraulic motor, the hydraulic motor 2 may be a fixed displacement type motor.

[0022] More specifically, as shown in Figure 2, the hydraulic motor 2 includes a drive unit 2b equipped with a rotating shaft 2a that is driven to rotate by the supply of pressurized oil, and a counterbalance valve 2e provided in the middle of the pipeline 2c from the suction port to the drive unit 2b and the pipeline 2d from the drive unit 2b to the discharge port.

[0023] Port a of the hydraulic motor 2 is connected to the tank 10 through the pipeline 9, and port b of the hydraulic motor 2 is connected to the tank 10 through the pipeline 9, the directional control valve 8, and the hydraulic motor 2. When the hydraulic pump 6 is rotated by the electric motor 7 for the pump and pressurized oil is supplied from the hydraulic pump 6 to port a of the hydraulic motor 2, the counterbalance valve 2e is pressed by the pressure acting on port a, switching to a position where pressurized oil is supplied to the drive unit 2b and pressurized oil is discharged from the drive unit 2b to port b, and the hydraulic motor 2 is rotated. Also, when pressurized oil is supplied from the hydraulic pump 6 to port b of the hydraulic motor 2, the counterbalance valve 2e is pressed by the pressure acting on port b, switching to a position where pressurized oil is supplied to the drive unit 2b and pressurized oil is discharged from the drive unit 2b to port a, and the hydraulic motor 2 is rotated. Therefore, when the electric motor 7 for the pump rotates the hydraulic pump 6, the hydraulic motor 2 is driven by the supply of pressurized oil from the hydraulic pump 6 and can rotate its rotating shaft 2a. On the other hand, when the supply of pressurized oil from the hydraulic pump 6 is interrupted, the counterbalance valve 2e switches to a position that shuts off the pipelines 2c and 2d, stopping the supply of pressurized oil to the drive unit 2b of the hydraulic motor 2 and stopping the rotating shaft 2a of the hydraulic motor 2.

[0024] Next, the load motor 3, although not shown in the diagram, comprises a stator and a rotor that can rotate around the stator's axis, and can output torque to rotate the rotor around its axis when current is supplied from the controller 4. The load motor 3 can be any motor that can output torque to rotate the rotor when current is supplied, so it can be a brushless DC motor, a brushed motor, an induction motor, etc.

[0025] The output shaft 3a of the rotor of the load electric motor 3 is connected to the rotating shaft 2a of the hydraulic motor 2 via a reduction gear 5 that reduces the rotational speed of the output shaft 3a and transmits it to the rotating shaft 2a of the hydraulic motor 2. Therefore, when the load electric motor 3 is the input side and the hydraulic motor 2 is the output side, the rotational speed of the output shaft 3a is increased compared to the rotational speed of the rotating shaft 2a of the hydraulic motor 2, and it rotates at a rotational speed obtained by multiplying the rotational speed of the rotating shaft 2a by the reciprocal of the reduction ratio.

[0026] The reduction gear 5 includes a gear 5a connected to the output shaft 3a of the load electric motor 3 via a coupling (not shown), and a gear 5b connected to the rotating shaft 2a of the hydraulic motor 2 via a coupling (not shown) that meshes with gear 5a. The gear 5b on the hydraulic motor 2 side has more teeth than the gear 5a on the load electric motor 3 side, thus reducing the rotational speed of the load electric motor 3 and transmitting it to the rotating shaft 2a of the hydraulic motor 2.

[0027] 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.

[0028] The hydraulic pump 6, acting as a hydraulic pump, is connected to the output shaft 7a of the electric motor 7 for the pump, whose drive shaft (not shown) is controlled by the controller 4. When rotated by the electric motor 7, it can draw hydraulic fluid from the tank 10 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.

[0029] The electric motor 7 for the pump, 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 for the pump 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.

[0030] The electric motor 7 for the pump 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. The electric motor 7 for the pump gradually increases its own rotational speed during the period from when the hydraulic motor 2 starts rotating until the rotational speed of the rotating shaft 2a reaches the rotational speed indicated by the test conditions, thereby increasing the rotational speed of the hydraulic motor 2.

[0031] On the other hand, after the rotational speed of the hydraulic motor 2 reaches a speed at which testing can be performed, the electric motor 7 for the pump is driven at a predetermined rotational speed to maintain the flow rate of pressurized oil supplied to the hydraulic motor 2 at the target discharge flow rate during the testing of the hydraulic motor 2, thereby rotating the hydraulic pump 6 at a constant rotational speed. Therefore, the hydraulic pump 6 supplies pressurized oil at the target discharge flow rate to the hydraulic motor 2 during the testing 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. During the testing of the hydraulic motor 2, the hydraulic pump 6 supplies pressurized oil at the target discharge flow rate to the hydraulic motor 2, so when the hydraulic motor 2 changes its tilt angle and reduces its capacity, the rotational speed of the hydraulic motor 2 increases.

[0032] 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.

[0033] As shown in Figure 3, the brake 20 is configured to include a friction plate 21 connected to the rotating shaft 2a of the hydraulic motor 2 via a reduction gear 5, friction members 22 and 23 positioned spaced apart from the friction plate 21 and movable relative to the friction plate 21, which suppress the rotation of the hydraulic motor 2 when they come into contact with the friction plate 21, cylinders 24 and 25 provided with pressure chambers 24b and 25b capable of pressing the friction members 22 and 23 against the friction plate 21, a pressure control valve 26 for adjusting the pressure supplied to the pressure chambers 24b and 25b, and a directional control valve 27 for switching between supplying and stopping pressure to the pressure chambers 24b and 25b.

[0034] The friction plate 21 is connected to the gear 5b via a shaft 21a so that it can rotate together with the gear 5b, which is connected to the hydraulic motor 2 of the reduction gear 5. Therefore, when the rotating shaft 2a of the hydraulic motor 2 rotates, the friction plate 21 rotates circumferentially together with the rotating shaft 2a.

[0035] The friction members 22 and 23 are positioned to sandwich the friction plate 21 from each other, and are movable relative to the friction plate 21. When they come into contact with the friction plate 21 and sandwich it, they exert a frictional force between themselves and the friction plate 21 that suppresses the rotation of the hydraulic motor 2.

[0036] Both cylinders 24 and 25 are cylindrical and integrally formed with the brake housing 30, with their openings facing the sides of the friction plate 21. Inside each cylinder, friction members 22 and 23 are attached to their tips, and pistons 24a and 25a, which form pressure chambers 24b and 25b, are housed within the cylinders 24 and 25.

[0037] Therefore, when the brake 20 supplies pressure to the pressure chambers 24b and 25b in the cylinders 24 and 25, it clamps the friction plate 21 with the friction members 22 and 23, generating a braking force that reduces the rotational speed of the rotating shaft 2a of the hydraulic motor 2 in accordance with the pressure inside the cylinders 24 and 25.

[0038] In this embodiment, the hydraulic power source that supplies pressurized oil into the pressure chambers 24b and 25b in cylinders 24 and 25 is a hydraulic pump 6. A flow divider valve 28 is provided in the middle of the pipeline 9 connecting the hydraulic pump 6 and the hydraulic motor 2, and a portion of the pressurized oil discharged by the hydraulic pump 6 can be supplied to cylinders 24 and 25 via the flow divider valve 28 and the brake passage 29 connecting the flow divider valve 28 to each cylinder 24 and 25.

[0039] A directional control valve 27 is provided in the middle of the brake passage 29. The directional control valve 27 has a valve body 27a which has an unload position 27b which shuts off the brake passage 29 and connects the pressure chambers 24b and 25b in each cylinder 24 and 25 to the tank 10 via the tank passage 31, and a load position 27c which connects the hydraulic pump 6 to the pressure chambers 24b and 25b in each cylinder 24 and 25 via the brake passage 29; a spring 27d which biases the valve body 27a to take the unload position 27b; and a solenoid 27e which, when energized, generates a biasing force that counteracts the biasing force of the spring 27d and switches the valve body 27a to the load position 27c. The directional control valve 27 is controlled by the controller 4.

[0040] Furthermore, a pressure control valve 26 is provided on the hydraulic pump 6 side of the brake passage 29, relative to the directional control valve 27. The pressure control valve 26 is an electromagnetic pressure reducing valve, and when the directional control valve 27 takes the load position 27c and pressure is loaded into the pressure chambers 24b and 25b, it can adjust the pressure in the pressure chambers 24b and 25b according to the amount of current supplied from the controller 4. Therefore, when the directional control valve 27 takes the load position 27c, the brake 20 can adjust the braking force that reduces the rotational speed of the rotating shaft 2a of the hydraulic motor 2 according to the amount of current supplied to the pressure control valve 26.

[0041] Next, as shown in Figure 4, the controller 4 is configured to include a pump control unit 4a that controls the hydraulic pump 6, a motor control unit 4b that controls the load electric motor 3, a brake control unit 4c, and an operation panel 4d that receives input of test conditions and instructions for starting and stopping 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.

[0042] The control panel 4d, 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 4d 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.

[0043] 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.

[0044] As shown in Figure 5, the pump control unit 4a includes a driver 4a1 that supplies current to the electric motor 7 for the pump, 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. The PWM signal is then applied to the driver 4a1 to rotate the electric motor 7 for the pump.

[0045] 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 for the pump. Although not shown, the driver 4a1 has several switches that, when turned on, connect the electric motor 7 for the pump to the power source and supply current to the windings, and when turned off, disconnect the connection between the windings of the electric motor 7 and 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 for the pump.

[0046] When the test of the hydraulic motor 2 is started, the pump control unit 4a supplies current to the electric motor 7 for the pump to rotate the hydraulic pump 6. The pump control unit 4a gradually increases the rotational speed of the electric motor 7 until the discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate, gradually increasing the discharge flow rate of the 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 discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate, 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 4a2 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 voltage can be applied to the electric motor 7.

[0047] Specifically, 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 for the pump 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, the signal generation unit 4a2 generates a PWM signal so as to increase the voltage applied to the electric motor 7 for the pump by X volts every t2 seconds, where t2 is 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 for the pump 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 for the pump 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 until the rotational speed reaches the test rotational speed, which is the rotational speed at the time of performing a test determined by the test conditions, based on the discharge flow rate of the hydraulic pump 6.

[0048] 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, thereafter, the signal generation unit 4a2 obtains the target voltage of the electric motor 7 for the pump so that the discharge flow rate of the hydraulic pump 6 becomes the target flow rate, and generates a PWM signal to apply a voltage equal to the target voltage to the electric motor 7 for the pump and outputs it to the driver 4a1.

[0049] 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 rotational speed to be tested. In this way, the rotational speed of the hydraulic motor 2 increases rapidly from the time it starts to rotate until it reaches a rotational speed slightly lower than the test rotational speed, and then the increase in 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 rotational speed at which the test can be performed (test preparation time), and suppresses the rotational speed from overshooting the test rotational speed. Furthermore, even if the rotational speed overshoots the 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 test rotational speed.

[0050] 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 for the pump 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 for the pump 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 rate of increase of the hydraulic motor 2 increases, and when the discharge flow rate of the hydraulic pump 6 exceeds the flow rate threshold, the rate of increase of the hydraulic motor 2 decreases. Alternatively, the signal generation unit 4a2 may generate a PWM signal that increases the voltage supplied to the electric motor 7 for the pump by a predetermined X1 volt every predetermined t3 seconds when the discharge flow rate of the hydraulic pump 6 is within the range of the flow rate threshold, and generate a PWM signal that increases the voltage supplied to the electric motor 7 for the pump by a value greater than X1 by X2 volts every t3 seconds when the discharge flow rate of the hydraulic pump 6 is within the range of 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 within the range of 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 within the range of the flow rate threshold.

[0051] 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 value 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 for the pump because it is easily affected by the efficiency and inertia of the hydraulic motor 2. Therefore, 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 is less affected by the efficiency and inertia of the hydraulic motor 2 and allows for more accurate control of the hydraulic pump 6.

[0052] 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 the hydraulic motor 2 can rotate at at the test rotation speed, which is the rotation speed at which the test can be performed. In addition, 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 until the discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate.

[0053] Furthermore, when the user presses the stop button on the control panel 4d, the signal generation unit 4a2 generates a PWM signal to gradually reduce the discharge flow rate of the hydraulic pump 6 and, after a predetermined stop processing time has elapsed, to stop the hydraulic pump 6. In other words, when the user instructs the test to stop, the signal generation unit 4a2 gradually decelerates the electric motor 7 for the pump by decreasing the duty cycle in the PWM signal over time to stop the hydraulic pump 6. Note that the test apparatus 1 may also perform an automatic stop process to stop the test after the hydraulic motor 2 test is completed, even without the stop button being pressed. In that case, the signal generation unit 4a2 only needs to obtain a PWM signal to stop the hydraulic pump 6 as described above after the hydraulic motor 2 test is completed.

[0054] Next, as shown in Figure 6, 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.

[0055] The rotation speed sensor 13, although not shown in the diagram, may be a rotary encoder or resolver that detects the rotation 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 rotation speed of the output shaft 3a by differentiating or filtering the rotational position.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 the load torque specified by the test conditions at the current rotational speed of the load electric motor 3.

[0060] 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.

[0061] The hydraulic motor 2 is tested after the hydraulic pump 6 has supplied pressurized oil at the target discharge flow rate to the hydraulic motor 2 and the rotational speed of the hydraulic motor 2's rotating shaft 2a has stabilized. Once the hydraulic motor 2 is ready for testing, the torque control unit 4b4 requests a current command to apply the load torque specified by the test conditions to the rotating shaft 2a of the hydraulic motor 2 in the opposite direction to the rotational direction of the rotating shaft 2a.

[0062] On the other hand, during the test preparation time from when the hydraulic motor 2 is started to rotate until the discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate and the rotation speed of the rotating shaft 2a stabilizes, the torque control unit 4b2 requests a current command to assist the rotation of the rotating 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 rotation direction of the rotating shaft 2a of the hydraulic motor 2.

[0063] 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 hydraulic motor 2 is ready for testing 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.

[0064] Furthermore, the torque control unit 4b2 requests a current command to cause the load electric motor 3 to output assist torque to help start the rotation of the rotating shaft 2a, even when the capacity of the hydraulic motor 2 is reduced to increase the rotational speed of the rotating shaft 2a. In addition, the torque control unit 4b4 requests a current command to prevent the load electric motor 3 from applying a load to the rotating shaft 2a of the hydraulic motor 2 when the user presses the stop button on the control panel 4d.

[0065] 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.

[0066] 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 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 current command to act on the rotating shaft 2a 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 to a high-speed test rotational speed, 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. The high-speed test rotation speed is the rotation speed at which the hydraulic motor 2 is tested while rotating it at high speed with a reduced capacity.

[0067] 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.

[0068] Furthermore, the torque control unit 4b2 reduces the capacity of the hydraulic motor 2, and when the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches the high-speed test rotational speed, it stops supplying 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 high-speed 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.

[0069] As shown in Figure 7, the brake control unit 4c determines the theoretical rotational speed Rt of the hydraulic motor 2 from the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 12, and the actual rotational speed Ra of the hydraulic motor 2 from the rotational speed of the load electric motor 3 detected by the rotational speed sensor 13. Based on the theoretical rotational speed Rt and the actual rotational speed Ra of the hydraulic motor 2, the brake control unit 4c controls the brake 20.

[0070] More specifically, the brake control unit 4c includes a brake necessity determination unit 4c1 that determines whether it is necessary to reduce the rotational speed of the hydraulic motor 2 with the brake 20, and a solenoid driver 4c2 that drives the pressure control valve 26 and the directional control valve 27 in the brake 20.

[0071] The brake necessity determination unit 4c1 compares the actual rotation speed Ra of the hydraulic motor 2 with a reference value Rt·s, which is obtained by multiplying the theoretical rotation speed Rt of the hydraulic motor 2 by a safety factor s. If the actual rotation speed Ra exceeds the reference value Rt·s, that is, Ra > Rt·s, it determines that deceleration of the hydraulic motor 2 by the brake 20 is necessary. If the actual rotation speed Ra is less than or equal to the reference value Rt·s, that is, Ra ≤ Rt·s, it determines that deceleration of the hydraulic motor 2 by the brake 20 is unnecessary.

[0072] The brake necessity determination unit 4c1 outputs a brake signal to the solenoid driver 4c2 if it determines that deceleration of the hydraulic motor 2 by the brake 20 is necessary, and does not output a brake signal if it determines that deceleration of the hydraulic motor 2 by the brake 20 is unnecessary.

[0073] If the discharge flow rate of the hydraulic pump 6 is Q, the current volume (displacement volume) of the hydraulic motor 2 is q, and the volumetric efficiency of the hydraulic motor 2 is ηv, then the theoretical rotational speed Rt can be calculated using the formula Rt = 1000 × ηv × Q / q. Therefore, the brake necessity determination unit 4c1 uses the above formula to determine the theoretical rotational speed Rt of the hydraulic motor 2. The discharge flow rate Q of the hydraulic pump 6 is detected by the flow sensor 12, the volume q of the hydraulic motor 2 is known because the current tilt angle of the hydraulic motor 2 can be determined, and the volumetric efficiency ηv of the hydraulic motor 2 is also known from the specifications of the hydraulic motor 2, so the brake necessity determination unit 4c1 can determine the theoretical rotational speed Rt.

[0074] Furthermore, the actual rotational speed Ra of the hydraulic motor 2 is determined by the fact that the output shaft 3a of the load electric motor 3 is connected to the rotating shaft 2a of the hydraulic motor 2 via a reduction gear 5, and the reduction ratio i is the value obtained by dividing the number of teeth of gear 5a of the reduction gear 5 by the number of teeth of gear 5b. The rotational speed Rm of the load electric motor 3 is detected by the rotational speed sensor 13 and can be determined by the brake control unit 4c. Therefore, the brake necessity determination unit 4c1 can determine the actual rotational speed Ra of the hydraulic motor 2 by multiplying the rotational speed Rm of the load electric motor 3 detected by the rotational speed sensor 13 by the reduction ratio i. In this embodiment, the actual rotational speed Ra of the hydraulic motor 2 is determined using the rotational speed sensor 13 of the load electric motor 3, but the actual rotational speed Ra of the hydraulic motor 2 may also be detected by separately providing a rotational speed sensor that detects the rotational speed of the rotating shaft 2a of the hydraulic motor 2.

[0075] The brake necessity determination unit 4c1 sets the safety factor s multiplied by the theoretical rotational speed Rt as follows. First, during the test preparation time in which the discharge flow rate of the hydraulic pump 6 is increased to increase the rotational speed of the hydraulic motor 2 until it reaches the test rotational speed, the brake necessity determination unit 4c1 sets the safety factor s to a value appropriate for the test preparation time. In this embodiment, the value of the safety factor s appropriate for the test preparation time is set in the range of 1.05 ≤ s ≤ 1.1, but it can be appropriately designed and changed according to the specifications of the test device 1 and the specifications of the hydraulic motor 2 being tested.

[0076] When the user presses the start button on the control panel 4d, the brake necessity determination unit 4c1 sets the safety factor s to a value appropriate for the test preparation time and does not change the value of the safety factor s until the discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate. However, when testing the hydraulic motor 2, the rotation speed of the hydraulic pump 6 is always increased first to increase the rotation speed of the hydraulic motor 2 to the test rotation speed. Therefore, when the test device 1 is started, the brake necessity determination unit 4c1 may reset the value of the safety factor s to the initial value, using a value appropriate for the test preparation time as the initial value of the safety factor s.

[0077] In contrast, during the test of the hydraulic motor 2, while controlling the discharge flow rate of the hydraulic pump 6 to the target discharge flow rate, the capacity of the hydraulic motor 2 is reduced until the rotational speed of the hydraulic motor 2 reaches the high-speed test rotational speed. Subsequently, when increasing the capacity of the hydraulic motor 2 to decelerate the rotational speed of the hydraulic motor 2 from the high-speed test rotational speed to the test rotational speed, the brake necessity determination unit 4c1 sets the safety factor s to a value suitable for decelerating the hydraulic motor 2 due to the capacity change. In this embodiment, the value of the safety factor s suitable for decelerating the hydraulic motor 2 due to the capacity change is set in the range of 0.8 ≤ s ≤ 0.9, but it can be appropriately designed and changed according to the specifications of the test apparatus 1 and the specifications of the hydraulic motor 2 being tested.

[0078] In this embodiment, the brake necessity determination unit 4c1 does not activate the brake 20 during testing of the hydraulic motor 2 except when the hydraulic motor 2 is decelerating. However, if braking of the hydraulic motor 2 by the brake 20 is to be performed during testing of the hydraulic motor 2 even when it is not decelerating, then a safety factor s suitable for testing of the hydraulic motor 2 at times other than deceleration should be set.

[0079] Furthermore, when the test of the hydraulic motor 2 is to be completed, the discharge flow rate of the hydraulic pump 6 is reduced while the rotational speed of the hydraulic motor 2 is decelerated, and finally the hydraulic pump 6 is stopped and the hydraulic motor 2 is stopped. During the stopping process time from when the hydraulic motor 2 is decelerated until it is stopped, the brake necessity determination unit 4c1 sets the safety factor s to a value appropriate for the stopping process time. In this embodiment, the value of the safety factor s appropriate for the stopping process time is set in the range of 1.05 ≤ s ≤ 1.1, but it can be appropriately designed and changed according to the specifications of the test apparatus 1 and the specifications of the hydraulic motor 2 being tested.

[0080] When the user presses the stop button on the control panel 4d or the test is stopped automatically, the brake necessity determination unit 4c1 sets the safety factor s to a value appropriate for the stop processing time, and does not change the value of the safety factor s until the hydraulic pump 6 is stopped and the discharge flow rate becomes 0.

[0081] Then, during the test preparation time, during the test of the hydraulic motor 2, from the time the rotation speed of the rotating shaft 2a decreases when the capacity is increased until it reaches the test rotation speed, and during the stopping process time, the brake necessity determination unit 4c1 compares the reference value Rt·s, obtained by multiplying the theoretical rotation speed Rt by a safety factor s, with the actual rotation speed Ra of the hydraulic motor 2 to determine whether or not deceleration of the hydraulic motor 2 by the brake 20 is necessary.

[0082] As mentioned above, the brake necessity determination unit 4c1 compares the reference value Rt·s, obtained by multiplying the theoretical rotation speed Rt by a safety factor s, with the actual rotation speed Ra of the hydraulic motor 2 to determine whether or not deceleration of the hydraulic motor 2 by the brake 20 is necessary. However, it is also possible to compare the theoretical rotation speed Rt with the actual rotation speed Ra of the hydraulic motor 2 without using the safety factor s, and determine that deceleration of the hydraulic motor 2 by the brake 20 is necessary if Ra > Rt, and that deceleration of the hydraulic motor 2 by the brake 20 is unnecessary if Ra ≤ Rt.

[0083] Next, when the solenoid driver 4c2 receives the brake signal output by the brake necessity determination unit 4c1, it supplies current to the directional control valve 27 to set the directional control valve 27 to the load position 27c, enabling it to supply pressure to the pressure chambers 24b and 25b of the brake 20. At the same time, it supplies current to the pressure control valve 26 so that the pressure in the pressure chambers 24b and 25b reaches a predetermined pressure, thereby applying a predetermined braking force to the rotating shaft 2a of the hydraulic motor 2 using the brake 20. The braking force is set so as to suppress the rotation of the rotating shaft 2a of the hydraulic motor 2 and rapidly reduce the rotational speed of the rotating shaft 2a, but not so as to abruptly stop the rotating shaft 2a. The braking force is determined by the pressure in the pressure chambers 24b and 25b, the pressure-receiving area of ​​the pistons 24a and 25a, and the coefficient of friction between the friction plate 21 and the friction members 22 and 23. Therefore, determining the braking force to be applied to the rotating shaft 2a of the hydraulic motor 2 determines the predetermined pressure in the pressure chambers 24b and 25b. Thus, determining the braking force determines the predetermined pressure in the pressure chambers 24b and 25b, and allows for the determination of how much the pressure from the hydraulic pump 6 should be reduced by the pressure control valve 26. Consequently, the amount of current that the solenoid driver 4c2 should supply to the pressure control valve 26 when a brake signal is input can also be uniquely determined. The braking force may be predetermined, but the brake necessity determination unit 4c1 may also determine the deviation between the actual rotational speed Ra of the hydraulic motor 2 and the reference value Rt·s, multiply this deviation by a gain to obtain the value as the braking force, and generate a brake signal that instructs the amount of current to achieve the braking force.

[0084] In this way, during the test preparation time, during the test of the hydraulic motor 2, from the time the rotational speed of the rotating shaft 2a decreases when the capacity is increased until it reaches the test rotational speed, and during the stopping process time, the brake control unit 4c compares the reference value Rt·s, obtained by multiplying the theoretical rotational speed Rt by a safety factor s, with the actual rotational speed Ra of the hydraulic motor 2 to determine whether or not it is necessary to decelerate the hydraulic motor 2 with the brake 20. If braking is necessary, the brake 20 exerts a braking force to suppress the rotation of the rotating shaft 2a of the hydraulic motor 2.

[0085] 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 the pump electric motor 7 in the pump control unit 4a and motor control unit 4b. This calculations include 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 processing unit in the controller 4 executes a program to perform the processing for the operating system, pump control unit 4a, motor control unit 4b, and brake control unit 4c, thereby realizing the pump control unit 4a, motor control unit 4b, and brake control unit 4c in the controller 4. If the data collected by the flow sensor 12, rotation speed sensor 13, and current sensor 14 can be used as test data, the flow sensor 12, rotation speed sensor 13, and current sensor 14 may be used as sensors for collecting test data.

[0086] Controller 4 is configured as described above, and the processes in Controller 4 will be explained below based on the flowchart shown in Figure 8. When the test start button on the control panel 4d is pressed down, Controller 4 drives the electric motor 7 for the pump to supply pressurized oil from the hydraulic pump 6 to the hydraulic motor 2, thereby starting 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.

[0087] Furthermore, the controller 4 increases the voltage applied to the electric motor 7 for the pump 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).

[0088] 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 for the pump in the previous step is applied to the electric motor 7 for the pump to increase the flow rate of the hydraulic pump 6 (step S2).

[0089] 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 for the pump that is X volts higher than the voltage previously applied to the electric motor 7 for the pump to increase the flow rate of the hydraulic pump 6 (step S5), and waits for t2 seconds to elapse, which is set to be longer than t1 seconds (step S6).

[0090] 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).

[0091] 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 for the pump that is X volts higher than the voltage previously applied to the electric motor 7 for the pump 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.

[0092] 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 for the pump 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).

[0093] 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 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.

[0094] Therefore, in the test apparatus 1, the time required for the rotational speed of the hydraulic motor 2 to reach a speed slightly lower than the 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 test rotational speed. Furthermore, even if the rotational speed does overshoot the test rotational speed, the amount of overshoot is small and the amount of voltage manipulation is also small, so the hunting of the rotational speed of the hydraulic motor 2 around the test rotational speed can be suppressed. Thus, according to 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, so the test preparation time from the start of the hydraulic motor 2 until the rotational speed of the hydraulic motor 2 stabilizes at the test rotational speed and the test can be performed can be shortened.

[0095] Furthermore, in the test apparatus 1 of this embodiment, the controller 4 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 monitors the flow rate of the pressurized oil (working fluid) detected by the flow sensor 12 and controls the rotation speed of the electric motor 7 for the pump to adjust the rate of increase of the hydraulic motor 2. With the test apparatus 1 configured in this way, compared to the case where the rotation speed of the hydraulic motor 2 is directly detected, 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 accuracy, and the test preparation time can be easily shortened.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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 high-speed 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.

[0101] When the rotational speed of the rotating shaft 2a stabilizes at the high-speed 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. In addition, during the test, the controller 4 also changes the tilt angle of the hydraulic motor 2 to increase its capacity and reduces the rotational speed of the hydraulic motor 2 from the high-speed test rotational speed to the test rotational speed, and collects test data.

[0102] Furthermore, once the test of the hydraulic motor 2 is complete, the controller 4 executes a stop process, gradually reducing the discharge flow rate of the hydraulic pump 6 over time to stop the hydraulic pump 6 and then the hydraulic motor 2 (step S9).

[0103] Next, the process related to the control of the brake 20 by the controller 4 will be explained. The process related to the control of the brake 20 by the controller 4 is performed during the test preparation time, while the capacity of the hydraulic motor 2 is increased and the rotation speed of the hydraulic motor 2 is reduced from the high-speed test rotation speed to the test rotation speed, and during the stop processing time.

[0104] The controller 4 sets the safety factor s to the value for the test preparation time during the test preparation time, to a value suitable for when the rotational speed of the hydraulic motor 2 is reduced from the high test rotational speed to the test rotational speed when the solenoid valve that changes the tilt angle of the hydraulic motor 2 to increase the volume is energized, and to the value for the stop processing time during the stop processing time.

[0105] Then, as shown in the flowchart in Figure 9, the controller 4 continuously detects the rotational speed of the hydraulic motor 2 during the test preparation time, from when a signal is input to the solenoid valve of the hydraulic motor 2 to increase the tilt angle and volume until the rotational speed of the hydraulic motor 2 is reduced to the test rotational speed, and also during the stop processing time (step S20).

[0106] The controller 4 then compares the detected actual rotational speed Ra of the hydraulic motor 2 with a reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by the safety factor s (step S21). If the comparison shows that Ra > Rt·s, the controller 4 determines that it is necessary to reduce the speed of the rotating shaft 2a by using the brake 20, and outputs a brake signal to the solenoid driver 4c2 to apply resistance to the rotation of the rotating shaft 2a of the hydraulic motor 2 and decelerate it (step S22).

[0107] On the other hand, if the comparison results in Ra ≤ Rt·s, the controller 4 determines that it is not necessary to reduce the speed of the rotating shaft 2a by the brake 20, and therefore does not output a brake signal to the solenoid driver 4c2, does not apply resistance to the rotation of the rotating shaft 2a of the hydraulic motor 2, and returns to the process of step S20.

[0108] During the test preparation time, while the capacity of the hydraulic motor 2 is increased and the rotation speed of the hydraulic motor 2 is reduced from the high test rotation speed to the test rotation speed, and during the stop processing time, the controller 4 repeatedly executes the flowchart process shown in Figure 9 to determine whether braking of the hydraulic motor 2 by the brake 20 is necessary, and if braking is necessary, the brake 20 applies braking force to reduce the rotation speed of the hydraulic motor 2.

[0109] During the test preparation time, the rotational speed of the hydraulic pump 6 is increased, and the rotational speed of the rotating shaft 2a of the hydraulic motor 2 is also increased. However, if the discharge flow rate of the hydraulic pump 6 fluctuates and decreases, the actual rotational speed Ra of the hydraulic motor 2 may exceed the theoretical rotational speed Rt due to the effect of inertia. In such cases, if the discharge flow rate of the hydraulic pump 6 decreases, the pressure at the discharge port of the hydraulic motor 2 decreases, the counterbalance valve 2e switches to the shut-off position, the pump chamber of the hydraulic motor 2 is closed, and the pressure on the discharge side may become excessive.

[0110] However, in the test apparatus 1 of this embodiment, if the actual rotational speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by a safety factor s during the test preparation time, the controller 4 activates the brake 20 to quickly reduce the rotational speed of the rotating shaft 2a of the hydraulic motor 2. This prevents the pump chamber of the hydraulic motor 2 from being closed by the counterbalance valve 2e, thus preventing the pressure inside the hydraulic motor 2 from becoming excessive. The safety factor s set during the test preparation time is set so that the reference value Rt·s is equal to or greater than the theoretical rotational speed Rt, because the risk of excessive pressure inside the pump chamber of the hydraulic motor 2 due to flow rate fluctuations of the hydraulic pump 6 is relatively low. In the test apparatus 1 of this embodiment, the brake 20 is activated when the actual rotational speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by a safety factor s. However, the brake 20 may also be activated when the actual rotational speed Ra exceeds the theoretical rotational speed Rt without using a safety factor s.

[0111] Furthermore, if the tilt angle of the hydraulic motor 2 is changed during testing to reduce its capacity, even if the discharge flow rate of the hydraulic pump 6 remains constant at the target discharge flow rate, the rotational speed of the hydraulic motor 2 increases by the amount of the reduced capacity, reaching the high-speed test rotational speed. In this state, if the tilt angle of the hydraulic motor 2 is changed to increase its capacity from the high-speed test rotational speed, even if the discharge flow rate of the hydraulic pump 6 remains constant at the target discharge flow rate, the rotational speed of the rotational shaft 2a of the hydraulic motor 2 will attempt to change to the test rotational speed by the amount of the increased capacity. However, since the rotational shaft 2a of the hydraulic motor 2 is connected to the load electric motor 3, even if the rotational shaft 2a attempts to decelerate, it is affected by the inertia of the load electric motor 3, and the rotational speed of the rotational shaft 2a does not quickly decelerate to the test rotational speed. In this embodiment, since the rotational shaft 2a of the hydraulic motor 2 is connected to the load electric motor 3 via a reduction gear 5, the inertial force of the load electric motor 3 acts on the rotational shaft 2a multiplied by the reciprocal of the reduction ratio, which further increases the time required to decelerate the rotational speed of the hydraulic motor 2.

[0112] Thus, although the capacity of the hydraulic motor 2 increases, it takes time for the rotational speed of the hydraulic motor 2 to decrease. As a result, the flow rate of pressurized oil required by the hydraulic motor 2 in accordance with the rotational speed of the rotating shaft 2a may exceed the discharge flow rate of the hydraulic pump 6. This can cause the pressure at the discharge port of the hydraulic motor 2 to drop, the counterbalance valve 2e to switch to the shut-off position, the pump chamber of the hydraulic motor 2 to close, and the pressure at the discharge port to become excessive.

[0113] However, in the test apparatus 1 of this embodiment, when the capacity of the hydraulic motor 2 is increased and the rotation speed of the hydraulic motor 2 is reduced from the high-speed test rotation speed to the test rotation speed, if the actual rotation speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotation speed Rt by the safety factor s, the controller 4 activates the brake 20 to quickly reduce the rotation speed of the rotating shaft 2a of the hydraulic motor 2. This prevents the pump chamber of the hydraulic motor 2 from being closed by the counterbalance valve 2e, and prevents the pressure inside the hydraulic motor 2 from becoming excessive.

[0114] Furthermore, when the capacity of the hydraulic motor 2 is increased and the rotational speed of the hydraulic motor 2 is reduced from the high-speed test rotational speed to the test rotational speed, the safety factor s set is set so that the reference value Rt·s is less than the theoretical rotational speed Rt, because the inertia of the load electric motor 3 has a significant influence in addition to the change in the capacity of the hydraulic motor 2, and there is a relatively large risk that the discharge flow rate of the hydraulic pump 6 will fall below the flow rate of pressurized oil required by the hydraulic motor 2, resulting in excessive pressure in the room. The test apparatus 1 operates the brake 20 so that the rotational speed of the rotating shaft 2a of the hydraulic motor 2 does not exceed the theoretical rotational speed Rt. In the test apparatus 1 of this embodiment, the brake 20 is operated when the actual rotational speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by the safety factor s. However, even when the capacity of the hydraulic motor 2 is increased and the rotational speed of the hydraulic motor 2 is reduced from the high-speed test rotational speed to the test rotational speed, the brake 20 may be operated if the actual rotational speed Ra exceeds the theoretical rotational speed Rt without using the safety factor s.

[0115] During the shutdown process, the rotational speed of the hydraulic pump 6 is gradually reduced to decrease the discharge flow rate of the hydraulic pump 6, and eventually the hydraulic pump 6 is stopped. As the discharge flow rate of the hydraulic pump 6 decreases in this way, the rotational speed of the rotating shaft 2a of the hydraulic motor 2 decreases. However, since the rotating shaft 2a of the hydraulic motor 2 is connected to the load electric motor 3, even if the rotating shaft 2a tries to decelerate, it is affected by the inertia of the load electric motor 3 and the rotational speed of the rotating shaft 2a does not decrease quickly. In this embodiment, since the rotating shaft 2a of the hydraulic motor 2 is connected to the load electric motor 3 via a reduction gear 5, the inertial force of the load electric motor 3 acts on the rotating shaft 2a multiplied by the reciprocal of the reduction ratio, which further increases the time it takes to decelerate the rotational speed of the hydraulic motor 2.

[0116] Therefore, during the shutdown process, the decrease in the rotational speed of the hydraulic motor 2 lags behind the decrease in the discharge flow rate of the hydraulic pump 6. As a result, the flow rate of pressurized oil required by the hydraulic motor 2 in accordance with the rotational speed of the rotating shaft 2a may exceed the discharge flow rate of the hydraulic pump 6. This can cause the pressure at the discharge port of the hydraulic motor 2 to drop, the counterbalance valve 2e to switch to the shut-off position, the pump chamber of the hydraulic motor 2 to close, and the pressure at the discharge port to become excessive.

[0117] However, in the test apparatus 1 of this embodiment, during the stopping process, if the actual rotational speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by a safety factor s, the controller 4 activates the brake 20 to quickly reduce the rotational speed of the rotating shaft 2a of the hydraulic motor 2. This prevents the pump chamber of the hydraulic motor 2 from being closed by the counterbalance valve 2e, thus preventing the pressure inside the hydraulic motor 2 from becoming excessive.

[0118] The safety factor s set during the stop processing time is smaller than the safety factor s set during the test preparation time because the inertia of the load electric motor 3 has a greater influence, and the risk of the discharge flow rate of the hydraulic pump 6 falling below the flow rate of pressurized oil required by the hydraulic motor 2, resulting in excessive pressure in the room, is greater than the risk during the test preparation time. The test apparatus 1 activates the brake 20 when the rotational speed Ra of the rotating shaft 2a of the hydraulic motor 2 exceeds the reference value Rt·s. In the test apparatus 1 of this embodiment, the brake 20 is activated when the actual rotational speed Ra exceeds the reference value Rt·s obtained by multiplying the theoretical rotational speed Rt by the safety factor s. However, the brake 20 may also be activated when the actual rotational speed Ra exceeds the theoretical rotational speed Rt without using the safety factor s.

[0119] Thus, during the test preparation time, while increasing the capacity of the hydraulic motor 2 and decelerating the rotation speed of the hydraulic motor 2 from the high test rotation speed to the test rotation speed, and during the stop processing time, if the rotation speed Ra of the hydraulic motor 2 is high and the discharge flow rate of the hydraulic pump 6 is less than the flow rate required by the hydraulic motor 2, the test apparatus 1 can activate the brake 20 to decelerate the rotation speed Ra of the hydraulic motor 2 to a rotation speed commensurate with the discharge flow rate of the hydraulic pump 6. Furthermore, when the brake necessity determination unit 4c1 determines the braking force from the rotation speed Ra and adjusts the braking force of the brake 20, the braking force can be adjusted according to the rotation speed Ra of the hydraulic motor 2, so the rotation speed of the hydraulic motor 2 can be quickly decelerated to a rotation speed commensurate with the discharge flow rate of the hydraulic pump 6.

[0120] As described above, the test apparatus 1 of this implementation includes a hydraulic pump 6 that supplies pressurized oil (working fluid) to the hydraulic motor 2 to rotate it, a load electric motor 3 connected to the rotating shaft 2a of the hydraulic motor 2 and capable of applying a load torque to the rotating shaft 2a in the opposite direction to the rotation direction of the hydraulic motor 2, a rotation speed sensor 13 capable of detecting the rotation speed of the hydraulic motor 2, and a braking means B that reduces the rotation speed of the hydraulic motor 2 when the theoretical rotation speed Rt obtained by the rotation speed sensor 13 from the flow rate of pressurized oil (working fluid) supplied to the hydraulic motor 2 exceeds the theoretical rotation speed Rt.

[0121] With the test apparatus 1 configured in this way, if the actual rotational speed Ra of the hydraulic motor 2 exceeds the theoretical rotational speed Rt, the braking means B reduces the rotational speed of the hydraulic motor 2. This prevents the amount of pressurized oil (working fluid) required by the hydraulic motor 2 from exceeding the discharge flow rate of the hydraulic pump 6. When the flow rate of pressurized oil (working fluid) supplied from the hydraulic pump 6 to the hydraulic motor 2 is insufficient, the braking means B reduces the rotational speed of the rotating shaft 2a of the hydraulic motor 2, causing the counterbalance valve 2e to enter the shut-off position and preventing excessive pressure inside the hydraulic motor 2. Therefore, with the test apparatus 1 of this embodiment, it is possible to prevent excessive pressure inside the hydraulic motor 2.

[0122] Furthermore, in the test apparatus 1 of this embodiment, during the test preparation time in which the hydraulic pump 6 is accelerated to increase the rotational speed of the hydraulic motor 2, the rotational speed of the hydraulic motor 2 is reduced based on the theoretical rotational speed Rt, which is obtained from the flow rate of the pressurized oil (working fluid) supplied to the hydraulic motor 2, and the actual rotational speed Ra of the hydraulic motor 2. Therefore, even if the discharge flow rate fluctuates when the hydraulic pump 6 is accelerated, it is possible to prevent the pressure inside the hydraulic motor 2 from becoming excessive.

[0123] Furthermore, in the test apparatus 1 of this embodiment, the hydraulic motor 2 is a variable displacement hydraulic motor, and the braking means B reduces the rotational speed of the hydraulic motor 2 when the capacity of the hydraulic motor 2 is increased. With the test apparatus 1 configured in this way, even when the rotational speed of the hydraulic motor 2 is difficult to decrease due to the inertia of the load electric motor 3 while the capacity of the hydraulic motor 2 is increased and the rotational speed of the hydraulic motor 2 is reduced from the high test rotational speed to the test rotational speed, the brake 20 is activated to quickly reduce the rotational speed of the rotational shaft 2a of the hydraulic motor 2, thereby preventing the pressure inside the hydraulic motor 2 from becoming excessive.

[0124] Furthermore, in the test apparatus 1 of this embodiment, during the stopping process time in which the hydraulic pump 6 is decelerated to stop the hydraulic motor 2, the rotational speed of the hydraulic motor 2 is decelerated based on the theoretical rotational speed Rt, which is obtained from the flow rate of the pressurized oil (working fluid) supplied to the hydraulic motor 2, and the actual rotational speed Ra of the hydraulic motor 2. Therefore, the rotational speed of the hydraulic motor 2 is decelerated in accordance with the deceleration of the hydraulic pump 6, thereby preventing excessive pressure inside the hydraulic motor 2 and quickly reducing the rotational speed of the hydraulic motor 2, thereby shortening the time required for the stopping process.

[0125] Furthermore, the braking means B includes a brake 20 comprising a friction plate 21 connected to the rotating shaft 2a of the hydraulic motor 2, friction members 22 and 23 positioned spaced apart from the friction plate 21 and movable relative to the friction plate 21, which suppress the rotation of the hydraulic motor 2 when they come into contact with the friction plate 21, cylinders 24 and 25 provided with pressure chambers 24b and 25b capable of pressing the friction members 22 and 23 against the friction members 22 and 23, and a pressure control valve 26 that adjusts the pressure supplied to the pressure chambers 24b and 25b.

[0126] With the test apparatus 1 configured in this way, the braking force that the brake 20 applies to the rotating shaft 2a of the hydraulic motor 2 can be adjusted by the pressure control valve 26. Furthermore, with the test apparatus 1, by appropriately adjusting the braking force of the brake 20, the rotational speed of the hydraulic motor 2 can be quickly adjusted to suit the discharge flow rate of the hydraulic pump 6.

[0127] In this embodiment, the test apparatus 1 applies braking force to the rotating shaft 2a of the hydraulic motor 2 using the brake 20. However, if it is necessary to reduce the rotational speed of the hydraulic motor 2, the controller 4 may control the load electric motor 3 to output torque to the rotating shaft 2a of the hydraulic motor 2 in the opposite direction to the rotational direction of the rotating shaft 2a, thereby reducing the rotational speed of the rotating shaft 2a. Thus, the braking means B may consist of the controller 4 and the load electric motor 3 instead of the controller 4 and the brake 20.

[0128] Furthermore, in the test apparatus 1 of this embodiment, the braking means B reduces the rotational speed of the hydraulic motor 2 when the actual rotational speed Ra exceeds a reference value obtained by multiplying the theoretical rotational speed Rt by a safety factor s. With the test apparatus 1 configured in this way, by appropriately using a safety factor s suitable for the test preparation time, a safety factor s suitable for reducing the rotational speed of the hydraulic motor 2 by increasing the capacity of the hydraulic motor 2, and a safety factor s suitable for the stop processing time, the rotational speed of the hydraulic motor 2 can be appropriately reduced, and the excessive pressure inside the hydraulic motor 2 can be further suppressed.

[0129] 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, so that a wide range of hydraulic motors 2 can be tested with a single test apparatus 1 while achieving miniaturization and cost reduction. In addition, when a reduction gear 5 is provided, the influence of the inertia of the load electric motor 3 becomes large, making it difficult for the rotational speed of the hydraulic motor 2 to decrease when the hydraulic motor 2 is decelerated. However, with the test apparatus 1 of this embodiment, a braking means B is provided to reduce the rotational speed of the hydraulic motor 2, so that the rotational speed of the hydraulic motor 2 can be quickly reduced even if the inertia of the load electric motor 3 is acting. In summary, the test apparatus 1 of this embodiment makes it possible to test a wide range of hydraulic motors 2 while preventing the pressure inside the hydraulic motor 2 from becoming excessive.

[0130] 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]

[0131] 1...Test apparatus, 2...Hydraulic motor, 3...Electric motor for load, 4...Controller, 5...Gear reducer, 6...Hydraulic pump (hydraulic pump), 13...Rotation speed sensor, 20...Brake, 21...Friction plate, 22,23...Friction members, 24b,25b...Pressure chamber, 26...Pressure control valve

Claims

1. A hydraulic pump that supplies working fluid to a hydraulic motor to rotate the hydraulic motor, A load motor connected to the rotating shaft of the hydraulic motor and capable of applying a load torque to the rotating shaft in the opposite direction to the rotation direction of the hydraulic motor, A rotation speed sensor capable of detecting the rotation speed of the hydraulic motor, The system includes a braking mechanism that determines the theoretical rotational speed of the hydraulic motor from the flow rate of the working fluid supplied to the hydraulic motor, and reduces the rotational speed of the hydraulic motor if the actual rotational speed of the hydraulic motor obtained by the rotational speed sensor exceeds the theoretical rotational speed. Testing equipment.

2. The aforementioned braking means is The brake comprises a friction plate connected to the rotating shaft of the hydraulic motor; a friction member positioned spaced apart from the friction plate and movable relative to the friction plate, which, when in contact with the friction plate, suppresses the rotation of the hydraulic motor; a cylinder provided with a pressure chamber capable of pressing the friction member against the friction plate; and a pressure control valve that adjusts the pressure supplied to the pressure chamber. The test apparatus according to feature 1.

3. The braking means reduces the rotational speed of the hydraulic motor when the actual rotational speed exceeds the value obtained by multiplying the theoretical rotational speed by a safety factor. The test apparatus according to feature 1.

4. The braking means reduces the rotational speed of the hydraulic motor by outputting torque from the load electric motor in the opposite direction to the rotational direction of the rotational shaft of the hydraulic motor. The test apparatus according to feature 1.

5. The hydraulic motor is a variable displacement hydraulic motor, The braking means reduces the rotational speed of the hydraulic motor when the hydraulic motor increases its capacity. The test apparatus according to any one of claims 1 to 4.

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