Test equipment

Abstract

To provide a test apparatus that can smoothly perform tests on multiple hydraulic motors with different output levels. [Solution] The test apparatus 1 of the present invention comprises an electric motor 3 connected to the rotating shaft 2a of a 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 electric motor 3. The controller 4 drives the 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.

Description

Technical Field

[0006] ,

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

Background Art

[0002] Conventionally, a test device for testing a hydraulic motor connects an electric motor to the rotating shaft of the hydraulic motor via a joint, supplies pressure oil from a hydraulic pump to the hydraulic motor to rotationally drive the hydraulic motor, and applies a load torque to the rotating shaft from the electric motor in the 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 and testing the performance of the hydraulic motor.

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, it is uneconomical to prepare one test device for each hydraulic motor with a different output. Therefore, it is preferable that one test device can test a plurality of hydraulic motors with different outputs.

[0005] When considering testing a plurality of hydraulic motors with different outputs using a test device, it is necessary to be able to apply a load to a hydraulic motor with a large output using an electric motor, and the use of an electric motor capable of corresponding to the output of the hydraulic motor that can be tested by the test device is required. ]|

[0006] Thus, conventional testing equipment requires the use of an electric motor capable of applying a sufficiently large load torque to the hydraulic motor with the highest output among the multiple hydraulic motors being tested, resulting in a large electric motor. When testing a small hydraulic motor with low output using such equipment, even if an attempt is made to start the hydraulic motor by rotating it with a hydraulic pump, the electric motor's inertial mass is large, and the resistance to starting the electric motor is too great, making it impossible to start the hydraulic motor and thus preventing the test from being performed.

[0007] Therefore, the present invention aims to provide a test apparatus that can smoothly perform tests on multiple hydraulic motors with different outputs. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention provides a test apparatus capable of applying a load torque to the rotating shaft of a hydraulic motor in the opposite direction to the rotation direction of the hydraulic motor, comprising an electric motor connected to the rotating shaft of the hydraulic motor and capable of applying a load torque to the rotating shaft of the hydraulic motor, and a controller for controlling the electric motor, wherein the controller drives the electric motor to apply an assist torque to the rotating shaft of the hydraulic motor at the start of rotation of the hydraulic motor to assist the rotation of the hydraulic motor.

[0009] With this test apparatus, even when testing a hydraulic motor with low output torque that cannot be started due to the resistance of the electric motor's inertia and static friction simply by supplying pressurized oil, the hydraulic motor can be started by adding an assist torque to the rotating shaft of the hydraulic motor to help it rotate.

[0010] Furthermore, if the hydraulic motor is a variable displacement motor whose rotational speed can be changed by changing its capacity, the controller in the test apparatus may drive an electric motor to add an assist torque to the rotational shaft of the hydraulic motor to assist the rotation of the hydraulic motor when the capacity of the hydraulic motor is reduced during the test.

[0011] According to the test apparatus, when the capacity of the hydraulic motor is reduced, the electric motor outputs assist torque, so even with a hydraulic motor with low output torque, the rotational speed of the rotating shaft can be rapidly increased to the rotational speed indicated by the test conditions. Therefore, according to the test apparatus, when increasing the rotational speed of the rotating shaft, the electric motor assists and reduces the inertial force, allowing the test to be performed smoothly.

[0012] Furthermore, the test apparatus may include a reduction gear between the electric motor and the rotating shaft to reduce the rotational speed of the electric motor and transmit it to the rotating shaft. With a test apparatus configured in this way, even if a small electric motor is used via the reduction gear, sufficient load torque can be applied to a large hydraulic motor. This makes it possible to test a wide range of hydraulic motors with a single test apparatus while also achieving miniaturization and cost reduction. [Effects of the Invention]

[0013] The test apparatus of the present invention can smoothly perform tests on multiple hydraulic motors with different outputs. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram showing the configuration of a test apparatus in one embodiment. [Figure 2] This is a configuration diagram of the controller of a test apparatus in one embodiment. [Figure 3] This is a diagram illustrating the configuration of the motor control unit in the controller. [Figure 4] This is a diagram showing the configuration of the pump control unit in the controller. [Figure 5] This is a flowchart showing the processing procedure of the controller of the test apparatus in one embodiment. [Modes for carrying out the invention]

[0015] The present invention will be described below based on the embodiments shown in the figures. As shown in Figure 1, the test apparatus 1 in one embodiment is configured to include an electric motor 3 connected to the rotating shaft 2a of the hydraulic motor 2 to be tested and capable of applying load torque to the rotating shaft 2a of the hydraulic motor 2, and a controller 4 that controls the electric motor 3. The test apparatus tests the hydraulic motor 2 by applying a load torque to the rotating shaft 2a of the hydraulic motor 2 in the opposite direction to the rotation direction of the rotating shaft 2a.

[0016] The following describes each part of the test apparatus 1. First, the hydraulic motor 2, which is the object of the test of the test apparatus 1, will be described. In this embodiment, the hydraulic motor 2 is equipped with a rotating shaft 2a for transmitting power to the outside and is a variable displacement hydraulic piston motor using working fluid as the working oil. Although not shown in the figures, it is equipped with a swash plate, a cylinder that drives the swash plate, and a solenoid valve for controlling the extension and retraction of the cylinder, and by changing the tilt angle of the swash plate, the displacement can be changed and the rotational speed can be changed even if the amount of working oil is constant.

[0017] Furthermore, the hydraulic motor 2 may be driven by a liquid other than hydraulic oil as the working fluid, and if it is a variable displacement type, it may be a vane motor in addition to a piston motor, in which the displacement can be changed by adjusting the eccentricity of the cam ring relative to the rotor. Also, since the test apparatus 1 can be used to test a fixed displacement type hydraulic motor, the hydraulic motor 2 may be a fixed displacement type motor.

[0018] Furthermore, the test apparatus 1 includes an electric motor 3 connected to the rotating shaft 2a of the hydraulic motor 2, a controller 4 for controlling the electric motor 3, a hydraulic pump 6 capable of supplying pressurized oil to the hydraulic motor 2 to rotate the rotating shaft 2a, an electric motor 7 for the hydraulic pump that drives the hydraulic pump 6, a directional control valve 8 that switches the direction in which the pressurized oil discharged from the hydraulic pump 6 is supplied to the hydraulic motor 2, and a pipeline 9 that exits the tank 10 and circulates back to the tank 10 through the hydraulic pump 6, the directional control valve 8, and the hydraulic motor 2. Thus, the hydraulic motor 2 can draw hydraulic oil from the tank 10 through the pipeline 9 and supply pressurized oil to the hydraulic motor 2 via the directional control valve 8.

[0019] Subsequently, the electric motor 3 includes a stator and a rotor rotatable about an axis with respect to the stator, although not shown in the drawings, and can output a torque for rotating the rotor about the axis by supplying current from the controller 4. The electric motor 3 may be a brushless DC motor, a brushed motor, an induction motor, or the like, as long as it can output a torque for rotating the rotor by current supply.

[0020] The output shaft 3a of the rotor of the electric motor 3 is connected to the rotary shaft 2a via a speed reducer 5 that decelerates the rotational speed of the output shaft 3a and transmits it to the rotary shaft 2a of the hydraulic motor 2. Therefore, when the hydraulic motor 2 is rotationally driven, the rotational speed of the output shaft 3a is increased from the rotational speed of the rotary shaft 2a of the hydraulic motor 2 and rotates at a rotational speed obtained by multiplying the rotational speed of the rotary shaft 2a by the reciprocal of the reduction ratio.

[0021] As described above, in the test apparatus 1 of the present embodiment, since the speed reducer 5 is provided, when current is applied to the electric motor 3 and a torque for driving the output shaft 3a in the opposite direction to the rotational direction of the rotary shaft 2a of the hydraulic motor 2 is output, a torque that is the reciprocal of the reduction ratio of the torque can be added to the rotary shaft 2a of the hydraulic motor 2. Therefore, in the test apparatus 1 of the present embodiment, by providing the speed reducer 5, it is possible to apply a sufficient load torque to the rotary shaft 2a of the hydraulic motor 2 even with a small-sized electric motor 3 having a small rated torque.

[0022] The hydraulic pump 6 as a hydraulic pump is connected to the output shaft 7a of an electric motor 7 for a hydraulic pump whose drive shaft outside the figure is controlled by the controller 4, and when rotationally driven by the electric motor 7 for a hydraulic pump, it can suck hydraulic oil from the tank 8 and supply pressure oil to the hydraulic motor 2. The hydraulic pump 6 may be a variable displacement type pump or a fixed displacement type pump, and may be a piston pump, a vane pump, a gear pump, or the like.

[0023] The electric motor 7 for the hydraulic pump only needs to be able to rotate the hydraulic pump 6 connected to the output shaft 7a by supplying current, so it can be a brushless DC motor, brush motor, induction motor, etc. The electric motor 7 for the hydraulic pump is controlled by the controller 4 and rotates the hydraulic pump 6 from a stopped state to supply pressurized oil to the hydraulic motor 2. From the time the hydraulic motor 2 starts rotating until the rotation speed of the rotating shaft 2a reaches the test rotation speed indicated by the test conditions for the hydraulic motor 2, the rotation speed of the hydraulic motor 2 is gradually increased to increase the rotation speed of the hydraulic motor 2.

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

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

[0026] As shown in Figure 2, the controller 4 comprises a motor control unit 4a that controls the electric motor 3, a pump control unit 4b that controls the hydraulic pump 6, and an operation panel 4c 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 electric motor 3 to apply load torque to the rotating shaft 2a of the hydraulic motor 2 according to the load pressure indicated by the predetermined test conditions.

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

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

[0029] As shown in Figure 3, the motor control unit 4a includes a driver 4a1 that supplies current to the electric motor 3, a torque control unit 4a2 that generates a current command that instructs the current to be supplied to the electric motor 3 based on the rotational speed of the electric motor 3 detected by the rotational speed sensor 12 and the load torque instructed by the test conditions, and a current control unit 4a3 that generates a PWM signal to be given to the driver 4a1 based on the difference between the current instructed by the current command and the current detected by the current sensor 13.

[0030] The rotation speed sensor 12, although not shown in the diagram, may be a rotary encoder or resolver that detects the rotation speed of the output shaft 3a relative to the stator 3b of the electric motor 3. 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.

[0031] The current sensor 13 detects the current flowing through the windings of the electric motor 3 (not shown in the figure). The current sensor 13 may be installed inside the electric motor 3, or it may be installed in the wiring connected to the windings of the driver 4a1, which will be described later.

[0032] 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 3. Although not shown, the driver 4a1 is equipped with multiple switches that, when turned on, connect the electric motor 3 to the power source and supply current to the windings, and when turned off, disconnect the electric motor 3 windings from the power source and stop supplying current to the windings. When a PWM signal is input to the driver 4a1, it turns on the switches according to the duty cycle indicated by the PWM signal and supplies current to the electric motor 3.

[0033] The torque control unit 4a2 determines the torque required for the electric motor 3, determines the target current necessary for the 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 4a2 controls the 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.

[0034] 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 4a2 monitors the rotational speed of the electric motor 3 and determines the current required for the electric motor 3 to output a load torque corresponding to the load pressure indicated by the test conditions at the current rotational speed of the electric motor 3.

[0035] Since the characteristics of the electric motor 3 used in the test apparatus 1 are known from the specifications of the electric motor 3, the torque control unit 4a2 can determine the current to be supplied to the electric motor 3 from the rotational speed of the 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 4a2 can determine the torque that the 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 electric motor 3 taking into account the reduction ratio of the reduction gear 5, the torque control unit 4a2 can determine the current command from the torque indicated by the test conditions and the rotational speed of the output shaft 3a.

[0036] The hydraulic motor 2 is tested as described later by supplying pressurized oil from the hydraulic pump 6 to the hydraulic motor 2 and rotating the rotating shaft 2a of the hydraulic motor 2 until the rotational speed of the rotating shaft 2a stabilizes at a predetermined first test rotational speed according to the test conditions. When the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches the first test rotational speed and the hydraulic motor 2 is ready for testing, the torque control unit 4a2 requests a current command to apply a load torque corresponding to the load pressure indicated by the test conditions to the rotating shaft 2a of the hydraulic motor 2 in the direction opposite to the rotational direction of the rotating shaft 2a.

[0037] On the other hand, during the test preparation time from when the hydraulic motor 2 is started to when its rotational speed reaches and stabilizes at the first test rotational speed, the torque control unit 4a2 requests a current command to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 by driving the output shaft 3a of the electric motor 3 to apply torque in a direction that matches the rotational direction of the rotational shaft 2a of the hydraulic motor 2 when starting the rotational speed of the rotational shaft 2a of the hydraulic motor 2. The controller 4 may continue to drive the electric motor 3 to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 until the rotational speed of the rotational shaft 2a of the hydraulic motor 2 reaches the first test rotational speed. Alternatively, the controller 4 may use an assist stop rotational speed lower than the first test rotational speed as a threshold and continue to drive the electric motor 3 to assist the rotation of the rotational shaft 2a of the hydraulic motor 2 until the rotational speed of the rotational shaft 2a of the hydraulic motor 2 reaches the assist stop rotational speed. Furthermore, the controller 4 may also drive the electric motor 3 only during the period from when it starts supplying pressurized oil from the hydraulic pump 6 to the hydraulic motor 2 until the rotating shaft 2a of the hydraulic motor 2 starts to rotate, thereby assisting the rotation of the rotating shaft 2a.

[0038] Thus, when the rotating shaft 2a of the hydraulic motor 2 is started to rotate, the torque control unit 4a2 requests a current command to the electric motor 3 to output a torque that assists in the rotation of the rotating shaft 2a. Then, when the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches a predetermined first test rotational speed and preparations for conducting the test are complete and test data can be collected, the torque control unit 4a2 requests a current command to the 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.

[0039] Furthermore, even when the capacity of the hydraulic motor 2 is reduced to increase the rotational speed of the rotating shaft 2a, the torque control unit 4a2 requests a current command to cause the electric motor 3 to output an assist torque to help start the rotation of the rotating shaft 2a.

[0040] The current control unit 4a3 receives feedback of the current detected by the current sensor 13, calculates the difference between the current instructed by the current command and the current detected by the current sensor 13, compensates for this difference proportionally and integrally or proportionally, differentially and integrally to determine the current to be supplied to the electric motor 3, generates a PWM signal to drive the switch of the driver 4a1 to realize the current to be supplied to the electric motor 3, and outputs the PWM signal to the driver 4a1.

[0041] Next, as shown in Figure 4, the pump control unit 4b includes a driver 4b1 that supplies current to the electric motor 7 for the hydraulic pump, and a signal generation unit 4b2 that generates a PWM signal to be given to the driver 4b1 based on the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 14, thereby controlling the electric motor 7 for the hydraulic pump that drives the hydraulic pump 6. The output shaft 7a of the electric motor 7 for the hydraulic pump is connected to the drive shaft of the hydraulic pump 6, and when driven by the pump control unit 4b, it rotates the hydraulic pump 6. When the hydraulic pump 6 is rotated, it draws hydraulic fluid from the tank 8 and discharges pressurized oil to the hydraulic motor 2. The driver 4b1 has the same configuration as the driver 4a1 in the motor control unit 4a.

[0042] When the pump control unit 4b starts testing the hydraulic motor 2, it supplies current to the electric motor 7 for the hydraulic pump to rotate the hydraulic pump 6. However, until the rotational speed of the rotational shaft 2a of the hydraulic motor 2 reaches the first test rotational speed required to obtain test data, it gradually increases the rotational speed and gradually increases the discharge flow rate of the pressurized oil from the hydraulic pump 6 over time. In other words, the signal generation unit 4b2 gradually increases the duty cycle of the PWM signal supplied to the driver 4b2 over time. Then, when the discharge flow rate of the hydraulic pump 6 detected by the flow sensor 14 rises to the target discharge flow rate, which is the flow rate when the rotational speed of the rotational shaft 2a of the hydraulic motor 2 matches the first test rotational speed, the pump control unit 4b controls the electric motor 7 for the hydraulic pump so that the discharge flow rate of the hydraulic pump 6 reaches the target discharge flow rate.

[0043] The torque control unit 4a2 generates a current command to apply the torque output by the electric motor 3 to the rotating shaft 2a in a direction that assists the rotation of the rotating shaft 2a when starting the rotation of the hydraulic motor 2. When the rotational speed of the rotating shaft 2a reaches the first test rotational speed, the torque control unit 4a4 generates a current command to stop the 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 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, the torque control unit 4a4 generates a current command to apply the torque output by the electric motor 3 to the rotating shaft 2a in a direction that assists the rotation of the rotating shaft 2a.

[0044] The torque control unit 4a2 monitors the rotational speed of the electric motor 3, and from the rotational speed of the 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 electric motor 3 to assist or inhibit the rotation of the rotating shaft 2a. Alternatively, the torque control unit 4a2 may estimate the rotational speed of the rotating shaft 2a of the hydraulic motor 2 based on the discharge flow rate of the hydraulic pump 6 obtained from the flow sensor 14. Furthermore, during testing of the hydraulic motor 2, when the capacity of the hydraulic motor 2 is reduced and the electric motor 3 is required to output assist torque, the torque control unit 4a2 receives a signal from the 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 4a2 outputs a current command from the electric motor 3 to generate assist torque that assists the rotation of the rotating shaft 2a.

[0045] Furthermore, when the hydraulic pump 6 discharges pressurized oil at a target discharge flow rate, the torque control unit 4a2 sets the rotational speed of the rotating shaft 2a of the hydraulic motor 2, which has a reduced capacity, as the second test rotational speed. When the rotational speed of the rotating shaft 2a of the hydraulic motor 2 reaches the second test rotational speed, the torque control unit 4a2 stops applying assist torque from the electric motor 3 to the rotating shaft 2a. Then, when collecting test data while the rotating shaft 2a is being driven at the second test rotational speed, the torque control unit 4a2 generates a current command so that the torque output by the electric motor 3 acts on the rotating shaft 2a as a load torque that hinders the rotation of the rotating shaft 2a.

[0046] Although not shown in the hardware diagram, the controller 4 includes, in addition to the drivers 4a1 and 4b1 in the pump control unit 4b that are necessary for driving the electric motor 3 and the electric motor 7 for the hydraulic pump, a CPU (Central Processing Unit) or similar processing unit, memory, an interface, and a bus that enables communication with the aforementioned devices. The motor control unit 4a and pump control unit 4b in the controller 4 are realized by the processing of the operating system, motor control unit 4a, and pump control unit 4b by the processing of the operating system, motor control unit 4a, and pump control unit 4b in the controller 4. If the data collected by the current sensor 13 and flow sensor 14 can be used as test data, the current sensor 13 and flow sensor 14 may be used as sensors for collecting test data.

[0047] Controller 4 is configured as described above, and the processes in Controller 4 will be explained below based on the flowchart shown in Figure 5. When the test start button on the control panel 4c is pressed down, Controller 4 drives the electric motor 7 for the hydraulic 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). Controller 4 also gradually increases the rotation speed of the electric motor 7 for the hydraulic pump to increase the flow rate of the hydraulic pump 6.

[0048] The controller 4 then determines whether an assist mode has been selected to assist the rotation of the hydraulic motor 2 when the electric motor 3 starts rotating (step S2). If the assist mode has been selected, the controller 4 drives the electric motor 3 and applies an assist torque in the direction that assists the rotation of the rotating shaft 2a, thereby assisting the rotation of the hydraulic motor 2 (step S3). If the assist mode has not been selected, the controller 4 proceeds to step S4 without outputting an assist torque from the electric motor 3.

[0049] Next, the controller 4 monitors the discharge flow rate of the hydraulic pump 6 and determines whether the discharge flow rate of the hydraulic pump 6 has reached the target discharge flow rate (step S4). If the discharge flow rate of the hydraulic pump 6 has not reached the target discharge flow rate, the rotational speed of the hydraulic motor 2 has not reached the first test rotational speed and the test cannot be started, so the controller 4 waits for a predetermined time to elapse. During this time, the controller 4 gradually increases the rotational speed of the electric motor 7 for the hydraulic pump to increase the flow rate of the hydraulic pump 6, so after the predetermined time has elapsed, the controller 4 performs the process of step S4 again.

[0050] On the other hand, if the determination in step S4 indicates that the discharge flow rate of the hydraulic pump 6 has reached the target discharge flow rate, the rotational speed of the rotating shaft 2a of the hydraulic motor 2 has reached the first test rotational speed. Therefore, the controller 4 determines whether the electric motor 3 is assisting the rotation of the hydraulic motor 2 (step S5). If the determination in step S4 indicates that the electric motor 3 is assisting, the controller 4 stops the electric motor 3 from supplying assist torque to the rotating shaft 2a of the hydraulic motor 2, and prevents the electric motor 3 from applying torque to the rotating shaft 2a so that the rotating shaft 2a rotates without load (step S6). If the determination in step S4 indicates that the electric motor 3 is not assisting, the controller 4 proceeds to step S7.

[0051] Next, the controller 4, knowing that the rotational speed of the hydraulic motor 2 has reached the first test rotational speed and the conditions for starting the test are met, instead of gradually increasing the rotational speed of the electric motor 7 for the hydraulic pump, controls the rotational speed of the electric motor 7 for the hydraulic pump so that the discharge flow rate of the hydraulic pump 6 stabilizes at the target discharge flow rate in preparation for the test (step S7). As a result, the rotational speed of the rotating shaft 2a of the hydraulic motor 2 stabilizes at the first test rotational speed, and the test can be performed.

[0052] Then, when the system is ready to perform the test, the controller 4 drives the 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 (step S8), and performs the test of the hydraulic motor 2 to collect test data (step S9).

[0053] Next, the controller 4 decides whether to change the volume of the hydraulic motor 2 and continue the test (step S10). If the decision in step S9 is to change the volume of the hydraulic motor 2, the volume of the hydraulic motor 2 is changed (step S11), and the process proceeds to step S2. On the other hand, if the decision in step S10 is not to continue the test, the process ends.

[0054] Furthermore, when the controller 4 receives a signal from the solenoid valve during the test to reduce the capacity of the hydraulic motor 2, it uses the input of this signal as a trigger to drive the electric motor 3 to apply an assist torque to the rotation axis 2a of the hydraulic motor 2 that matches the direction of rotation.

[0055] The controller 4 then continues to apply assist torque from the electric motor 3 to the rotating shaft 2a while monitoring the rotational speed of the hydraulic motor 2's rotating shaft 2a. When the rotational speed of the rotating shaft 2a reaches the second test rotational speed, the controller 4 stops the output of assist torque from the electric motor 3, so that the rotating shaft 2a rotates without load and no torque is applied to the rotating shaft 2a from the electric motor 3.

[0056] When the rotational speed of the rotating shaft 2a stabilizes at the second test rotational speed, the controller 4 drives the 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.

[0057] As described above, the test apparatus 1 of this embodiment includes an 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 electric motor 3. The controller 4 drives the 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.

[0058] 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 to rotate simply by supplying pressurized oil at the time of rotational start due to the resistance of the inertial mass and static friction of the electric motor 3, the hydraulic motor 2 can be started to rotate by adding an assist torque to the rotating shaft 2a of the hydraulic motor 2 at the time of rotational start of the hydraulic motor 2.

[0059] Therefore, according to the test apparatus 1 of this embodiment, even if a large electric motor 3 is installed to enable testing of large hydraulic motors with high output, testing of hydraulic motors 2 with low output can also be performed without difficulty. As described above, according to the test apparatus 1 of this embodiment, testing of multiple hydraulic motors 2 with different outputs can be performed smoothly, and a wide range of hydraulic motors 2 can be tested with a single test apparatus 1.

[0060] Furthermore, in the test apparatus 1 of this embodiment, the hydraulic motor 2 is a variable displacement motor whose rotational speed can be changed by changing its capacity, and the controller 4 drives the electric motor 3 to add assist torque to the rotation shaft 2a of the hydraulic motor 2 when the capacity of the hydraulic motor 2 is reduced during the test, thereby assisting the rotation of the hydraulic motor 2. When the capacity of the hydraulic motor 2 is reduced, the rotation shaft 2a of the hydraulic motor 2 will increase in speed, but when the rotation shaft 2a increases in speed, the output torque of the hydraulic motor 2 decreases and the inertial mass of the electric motor 3 acts on the rotation shaft 2a. In conventional test apparatuses, if the hydraulic motor 2 has a small output torque, the torque will be insufficient and the rotational speed will decrease, which may require time to recover the rotational speed or may cause the test to deviate from the test conditions and prevent the test from continuing. In contrast, with the test apparatus 1 of this embodiment, when the capacity of the hydraulic motor 2 is reduced, the electric motor 3 is made to output assist torque, so even if the hydraulic motor 2 has a small output torque, the rotational speed of the rotation shaft 2a can be quickly increased and raised to the second test rotational speed indicated by the test conditions. Based on the above, the test apparatus 1 of this embodiment allows for smooth testing by using the electric motor 3 to assist in increasing the rotational speed of the rotating shaft 2a, thereby reducing the inertial force.

[0061] Furthermore, the test apparatus 1 of this embodiment is equipped with a reduction gear 5 between the electric motor 3 and the rotating shaft 2a, which reduces the rotational speed of the electric motor 3 and transmits it to the rotating shaft 2a. With the test apparatus 1 configured in this way, even if a small electric motor 3 is used via the reduction gear 5, a sufficient load torque can be applied to the large hydraulic motor 2. Thus, it is possible to test a wide range of hydraulic motors 2 with a single test apparatus 1 while also achieving miniaturization and cost reduction.

[0062] 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]

[0063] 1...Testing apparatus, 2...Hydraulic motor, 2a...Rotating shaft, 3...Electric motor, 4...Controller, 5...Gear reducer

Claims

1. A test apparatus capable of applying a load torque to the rotating shaft of a hydraulic motor in the opposite direction to the rotation direction of the hydraulic motor, An electric motor connected to the rotating shaft of the hydraulic motor and capable of applying load torque to the rotating shaft of the hydraulic motor, The system includes a controller that controls the aforementioned electric motor, The aforementioned controller, The electric motor is driven so as to apply an assist torque to the rotating shaft of the hydraulic motor when the hydraulic motor starts rotating, thereby assisting the rotation of the hydraulic motor. A test apparatus characterized by the following features.

2. The hydraulic motor is a variable displacement motor whose rotational speed can be changed by changing its capacity, The controller drives the electric motor to apply an assist torque to the rotating shaft of the hydraulic motor to assist the rotation of the hydraulic motor when reducing the capacity of the hydraulic motor during testing. The test apparatus according to feature 1.

3. A reduction gear is provided between the electric motor and the rotating shaft to reduce the rotational speed of the electric motor and transmit it to the rotating shaft. The test apparatus according to feature 1.

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