Vibration test apparatus

Abstract

This vibration test apparatus is provided with linear motors that reciprocate a movable element in a linear direction. The plurality of linear motors are installed so as to be able to reciprocate each movable element in a parallel direction and vibrate a support member that supports a sample, thereby vibrating the sample in the linear direction.

Description

Vibration Test Equipment

[0001] The present invention relates to a vibration test device that applies vibration to a test specimen.

[0002] Vibration testing equipment that applies forced vibration to evaluate the durability and performance of various components and equipment is known. This type of vibration testing equipment often uses hydraulic equipment to vibrate heavy test specimens. However, hydraulic vibration testing equipment requires a large hydraulic power source, consumes high energy, and has high maintenance costs. Furthermore, hydraulic control valves have poor output characteristics for high-frequency (40 Hz or higher) acceleration, and do not operate as commanded. This requires time-consuming processing to scale up or down the command signal. For this reason, in recent years, devices using linear motors (actuators) that move in a linear direction have been considered (see, for example, Patent Documents 1 and 2). This linear motor-based vibration testing equipment requires no electricity except during operation, which reduces energy consumption. It is simple and easy to use, eliminating the need for maintenance such as changing lubricating oil or disassembling and cleaning hydraulic valves. Furthermore, it operates as commanded for relatively high-frequency acceleration vibrations up to about 100 Hz, allowing testing to be performed without signal processing time. Another advantage is that there is little time delay in response to commands (less than a fraction of that of hydraulic pressure) and it has good response to changes in command values ​​in real time during tests simulating operating conditions, making it easy to use.

[0003] Patent No. 5466031 Patent No. 4885222

[0004] However, in such a linear motor vibration test device, the driving force of the linear motor is smaller than that of a hydraulic actuator of a similar size. As a result, the output driving force is insufficient to support a test specimen that requires a large driving force, such as a shock absorber that is attached to a wheel to reduce wheel vibration to ensure vehicle running quality and evaluate the durability and performance of the shock absorber. Furthermore, if the output driving force is small, it is impossible to apply large acceleration vibrations to the test specimen during the vibration test.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a linear motor type vibration testing device that can apply sufficient vibration even to a heavy test piece.

[0006] One aspect of the invention of a linear motor type vibration test device that solves the above problem is a vibration test device that is equipped with a linear motor that moves a movable element back and forth in a linear direction and applies linear vibration to a test piece, and is characterized in that multiple linear motors are installed so that their respective movable elements can move back and forth in parallel directions, thereby vibrating a support member that supports the test piece.

[0007] Thus, according to one aspect of the present invention, it is possible to provide a linear motor type vibration testing device that can vibrate the support member that supports the test specimen using the driving force of multiple linear motors, and that can apply sufficient vibration even to heavy test specimens.

[0008] FIG. 1 is a front view showing the overall schematic configuration of an automotive vibration test system equipped with a linear motor vibration test device according to one embodiment of the present invention. FIG. 2 is a conceptual structural diagram showing the overall schematic configuration of a linear motor vibration test device. FIG. 3 is a diagram showing the structure of one linear motor, where (a) is a partially enlarged vertical cross-sectional view of the upper part as seen from the same direction as FIG. 2, and (b) is a schematic diagram showing the magnet configuration of the mover. FIG. 4 is a horizontal cross-sectional view of one linear motor. FIG. 5 is a conceptual block diagram explaining the control of the vibration test system. FIG. 6 is a vertical cross-sectional view showing a state of one linear motor before test preparation. FIG. 7 is a vertical cross-sectional view showing a state of one linear motor during preparation. FIG. 8 is a vertical cross-sectional view showing a state of one linear motor during test.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figures 1 to 8 show a linear motor type vibration testing device according to an embodiment of the present invention.

[0010] 1 , a vibration test device 10 is assembled to a vibration test system 100 for an automobile (test specimen) C, which performs evaluation tests for durability, vibration control performance, etc. by applying vibrations that move each of the four wheels W of the automobile C up and down in a vertical direction V (moving back and forth in a linear direction). The vibration test system 100 is constructed so that a vibration test can be performed while the automobile C, which is supported so that each of the four wheels W cannot rotate, is placed stationary on an adjustment plate 101. Here, in this vibration test system 100, the vibration test device 10 for each of the four wheels W is placed in a space 103 excavated in the ground surface (height) on which the automobile C travels, and the vibration test device 10 is installed below an adjustment plate 101 that is prepared to restrain each of the four wheels W so that they cannot rotate. The adjustment plate 101 is equipped with a mechanism (not shown) that adjusts the position of the automobile C in the forward and backward directions and left and right directions at ground level.

[0011] Four sets of this vibration test apparatus 10 are mounted on a vibration test system 100 so as to function positioned below adjustment plates 101 for each of the four wheels W of the automobile C, and vibration is controlled by a control system (control device) 50 (described later) to apply the same or individual vibration to each of the four wheels W so as to reproduce the behavior of the wheels from the road surface during driving, thereby outputting the desired driving force. Here, a control system 50 may be provided for each of the four sets of vibration test apparatuses 10 and set and control them individually, but in this embodiment, the control system 50 is configured to control all four sets of vibration test apparatuses 10 in an integrated manner so as to drive them together or separately to perform vibration tests.

[0012] 2, the vibration test device 10 has two linear motors (actuators) 20 and one air spring mechanism 40 housed integrally in a housing 10F. In this vibration test device 10, support members 11 connected and fixed under adjustment plates 101 for each of the four wheels W of the vibration test system 100 are connected to one end of the movers 21, which are plate-like members of the two linear motors 20, and the moving plate 41, which is a plate-like member of the one air spring mechanism 40, and are integrated together, so that the movers 21 of these linear motors 20 together with the moving plate 41 of the air spring mechanism 40 move up and down (reciprocate) in the linear vertical direction V to apply vibration to the four wheels W of the automobile C on the adjustment plates 101. That is, the movers 21 of the multiple linear motors 20 and the moving plates 41 of the air spring mechanisms 40 are connected at one end to a common support member 11 and reciprocate in vertical and parallel directions to vibrate the wheels W (shock absorbers) of the automobile C under test, thereby enabling a vibration test to be performed. The vibration test device 10 is positioned and fixed by connecting a base member 10Fb at the bottom of the housing 10F to a base within the installation space 103 of the vibration test system 100.

[0013] The linear motors 20 are arranged at symmetrical positions sandwiching the air spring mechanism 40, and the pair of movers 21 move up and down simultaneously (synchronized), thereby applying two sets of driving forces to the support member 11 and applying vibrations to the four wheels W of the automobile C on the adjustment plate 101, thereby performing a vibration test of a shock absorber (not shown). Here, in this embodiment, the vibration test device 10 equipped with two sets of linear motors 20 will be described as an example, but it goes without saying that it is not limited to two sets, and may be equipped with three or more sets.

[0014] Specifically, as shown in Figures 3 and 4, the linear motor 20 is assembled in the form of a rectangular parallelepiped, with the wall portions 10Fw of the housing 10F positioned at the locations facing the plate-shaped movable elements 21 and the legs 10Ff sandwiched between the wall portions 10Fw, and a pair of stators 31 are fixed to the inner surface of the wall portions 10Fw so as to face each of the plate-shaped movable elements 21 that move up and down while facing each other.

[0015] The mover 21 of the linear motor 20 is provided with a yoke 23 made of a plate-shaped iron member that allows magnetic flux to pass through so as to receive power (magnetic force) that moves it up and down while facing a stator 31 that is installed on the inner surface of the wall 10Fw of the housing 10F, and magnets 25 are arranged so that positive and negative poles are alternately positioned at the locations of the yoke 23 that face the stator 31. In addition, the stator 31 of the linear motor 20 is provided with a coil (not shown) that is supplied with power from a power source, thereby loading a magnetic force that moves the mover 21 back and forth.

[0016] The movable element 21 of this linear motor 20 is supported by a pair of end edge rollers 33 rotatably supported on the legs 10Ff of the housing 10F, one set of which is supported in face-to-face contact with both end edges 21e of the plate-shaped member in the width direction S so as to be able to move up and down freely; and similarly, two sets of pair of end surface rollers 35 rotatably supported on the wall portions 10Fw of the housing 10F are supported by two sets of pair of end surface rollers 35 rotatably supported on the wall portions 10Fw of the housing 10F, each of which is supported in face-to-face contact with both end surfaces 21s of the plate-shaped member in the width direction S so as to be able to move up and down freely.

[0017] Furthermore, in the mover 21 of the linear motor 20, magnets 25a (e.g., N poles) and magnets 25b (e.g., S poles) are arranged so that magnetic poles (S poles, N poles) alternate in the up-down direction V of the yoke 23 and the magnetic poles are reversed on both sides in the thickness direction T of the yoke 23. Note that durability is ensured by fixing backing plates 39a to both end edges 21e in the width direction S with which the end edge rollers 33 rotatably come into face-to-face contact, and by fixing backing plates 39b to both end surfaces 21s in the width direction S with which the end surface rollers 35 rotatably come into face-to-face contact, but these may be omitted and the various rollers 33, 35 may be supported by directly contacting the yoke 23 face-to-face.

[0018] Here, by adopting such a configuration for the mover 21 of the linear motor 20, the magnet 25 can be arranged without considering magnetic pole saturation caused by the magnet 25, and the thickness of the yoke 23 in the thickness direction T can be minimized. Furthermore, the mass of the mover 21 can be reduced, and the output acceleration and responsiveness of the vibration operation can be improved. Note that because the mover 21 does not include the weight of the stator 31 or the rollers 33 and 35 on the housing 10F side, there is no need to unnecessarily increase the magnetic force (output) when moving up and down, and it is possible to avoid a decrease in acceleration and a decrease in lifespan due to weight.

[0019] Returning to Figure 2, the air spring mechanism 40 is housed within the housing 10F so as to be positioned between the two sets of linear motors 20, and the moving plate 41 of the air spring mechanism 40 is supported by two sets of pairs of rollers 43, 45 that are positioned above and below and are freely rotatable, in face-to-face contact with both side surfaces 41s, respectively, so that they can move up and down freely, just like the plate-shaped movable element 21 of the linear motor 20.

[0020] The movable plate 41 of the air spring mechanism 40 is formed in a hollow plate shape with an internal space 41a, and the opposite end 41e relative to the support member 11 is open, and the opposite end 41e relative to the support member 11 is formed with plate-shaped ribs 41r that protrude outward perpendicularly from both side surfaces 41s.

[0021] The air spring mechanism 40 includes a damper 47 disposed between the wall portions 10Fw of the housing 10F on both sides so as to cover the entire end portion 41e of the movable plate 41, which has the plate-like rib 41r, and the damper 47 is in contact with an end edge 43re of the plate-like rib 41r of the movable plate 41 so as to be able to move up and down while maintaining airtightness. The damper 47 of the air spring mechanism 40 has an internal space 47a that communicates with the internal space 41a via an opening 41o between the plate-like ribs 41r of the movable plate 41, and a valve 47v that fills (encloses) the internal spaces 47a, 41a with outside air A at a desired pressure and maintains (seals) the internal spaces 47a, 41a in a closed state is disposed at a bottom 47b.

[0022] With this structure, the air spring mechanism 40 can urge the moving plate 41 upward, that is, in a direction parallel to the direction of movement of the mover 21 of the linear motor 20, by filling a desired amount of external air A from a pressure source P (shown in FIG. 5) into the internal space 47a and the internal space 41a of the moving plate 41 via the valve 47v of the damper 47, using the desired air pressure as an elastic force, and thus functions as an elastic adding mechanism that supports the support member 11 together with the pair of linear motors 20. The air pressure of the air spring mechanism 40 can be adjusted by adjusting the amount of external air A filled in the damper 47 and the internal spaces 47a, 41a of the moving plate 41 using the valve 47v, and the elastic force (air pressure) applied to the support member 11 can be adjusted according to the weight of the test piece.

[0023] As shown in FIG. 5, the vibration test device 10 is configured so that the behavior of the support member 11 is detected by the up and down movement of each of the movers 21 of the pair of linear motors 20 using high-resolution encoders 57 installed on the wall 10Fw of the housing 10F on the stator 31 side, and the drive of the pair of linear motors 20 and the air spring mechanism 40 is controlled by a control system (control unit) 50 based on the detection information (signals) of each encoder 57.

[0024] The control system 50 is constructed so that a host control device 51, an air tandem controller 53, and a pair of motor drivers 55A, 55B are connected so as to be able to exchange various signals and drive them in conjunction with one another, and the host control device 51 passes drive signals to the controller 53 and the motor drivers 55A, 55B so as to provide overall control of the entire vibration test apparatus 10, causing the motor drivers 55A, 55B to send drive power to the stator 31 of the linear motor 20 to move the mover 21 up and down, and also opens and closes a valve 47v in the damper 47 of the air spring mechanism 40 to supply compressed air A from the pressure source P and adjust the amount of air filled into the internal spaces 41a, 47a of the moving plate 41 and the damper 47, thereby adjusting the elastic force that urges the moving plate 41 upward.

[0025] Specifically, in order to carry out a vibration test on the test piece (automobile) C based on various setting input information in accordance with a control program previously stored in a memory (not shown), the upper control device 51 acquires displacement information of the mover 21 (support member 11) from the encoder 57 via the motor drivers 55A, 55B to derive the vibration conditions, and sends instruction information according to the vibration conditions to the motor drivers 55A, 55B to supply a drive current to the stator 31 of each linear motor 20.

[0026] This upper control device 51 is configured to send instruction information corresponding to the support conditions of the test specimen C to the controller 53 based on displacement information from the encoder 57 obtained via motor drivers 55A and 55B, so that a vibration test of the test specimen C can be carried out in accordance with the control program, and to supply a driving current that adjusts and controls the opening and closing of the valve 47v of the damper 47 of the air spring mechanism 40.

[0027] Here, the signal commands used in the above-mentioned sections 51, 53, 55A, and 55B of the control system 50 may be either analog signals or digital signals, and the selection may be made taking into consideration the effects of noise, etc. In this control system 50, the wiring lengths of the signal lines and power supply lines of the pair of motor drivers 55A and 55B and encoder 57, which are driven with similar functions, are made equal so that various conditions (signal strength, timing, etc.) are equalized.

[0028] The air tandem controller 53, like the host control device 51, is configured to execute drive control for generating in the air spring mechanism 40 a pressure that maintains the automobile C at a desired height so that a vibration test can be performed on the specimen C in accordance with a control program previously stored in a memory (not shown). At this time, the controller 53 is configured to supply a drive current that controls the opening and closing of the valve 47v so that compressed air A is filled from the pressure source P into the damper 47 of the air spring mechanism 40 and the internal spaces 47a, 41a of the moving plate 41, so that the air pressure is such that an elastic force is exerted to support the specimen C at a height that can ensure the amplitude during the vibration test independently, without cooperating with the drive force of the pair of linear motors 20.

[0029] In detail, the controller 53 of this embodiment monitors the driving force (driving current supplied to the stator 31) output by the pair of linear motors 20 via the motor drivers 55A, 55B, and controls the opening and closing of the valve 47v of the damper 47 of the air spring mechanism 40 so that the load as thrust becomes zero, thereby closing the valve 47v at the timing when the test piece C is supported independently, thereby maintaining the supported state. In short, the air pressure (elastic force) of the air spring mechanism 40 is increased to an extent that the driving force of the linear motor 20 can be reduced to zero, and a large air pressure is secured that is large enough to prevent the vibrations of the vibration test by the linear motor 20 from fluctuating the air pressure of the air spring mechanism 40, thereby preventing large fluctuations in the air pressure from becoming a disturbance in the vibration test.

[0030] Here, when the vibration test device 10 is used as a vibration test device for shock absorbers of wheels W of an automobile C, when the four wheels of the automobile C are placed on or removed from the adjustment plate 101, a switch is provided to display "preparing," "waiting," or "testing" to prevent the vibration operation from inadvertently starting, and the vibration test by the pair of linear motors 20 will not start unless the controller 53 detects that the test specimen C is being supported alone by the air spring mechanism 40, and the vibration test of the test specimen C begins by turning on the test start switch.

[0031] In short, as shown in FIG. 6, before the wheels W (four wheels) of the automobile C are prepared to be placed on the adjustment plate 101, the vibration test device 10 does not supply compressed air A to the damper 47 of the air spring mechanism 40, and the internal space 47a is at the minimum volume V1, and the lowest ends of the movers 21 of the pair of linear motors 20 enter the escape grooves 29 that open into the base member 10Fb of the housing 10F, positioning the support member 11 at the pre-preparation height.

[0032] 7 , in the vibration test apparatus 10, while preparing to hold the wheels W (four wheels) of the automobile C mounted on the adjustment plate 101 at the vibration test height, the host control device 51 and the controller 53 supply compressed air A from the pressure source P into the damper 47 of the air spring mechanism 40 so that the internal space 47a is at the test volume V2, and the displacement of the mover 21 is detected based on a detection signal from the encoder 57, and the valve 47v is controlled to open and close, thereby positioning the support member 11 at the preparation / pre-test (during-test) height. At this time, the host control device 51 may supply power to the stators 31 of the pair of linear motors 20 to drive the movers 21 and thereby assist in the lifting of the specimen C. In this case, after the support member 11 has been held at the preparation height, the power supply to the stators 31 of the pair of linear motors 20 is gradually reduced to zero the lifting load on the specimen C caused by the movers 21.

[0033] 8, during a test in which the wheels W (four wheels) of the automobile C placed on the adjustment plate 101 are held at the vibration test height, the controller 53 keeps the valves 47v of the dampers 47 closed to maintain the holding of the specimen C at the test height by the air spring mechanism 40, and the host control device 51 causes the motor drivers 55A, 55B to supply current to the stators 31 of each pair of linear motors 20 based on displacement information from the encoder 57, thereby performing a vibration test on the specimen C. Note that FIG. 8 illustrates the timing during a test in which upward acceleration is applied to the support member 11 to apply a shock to the wheels W of the automobile C placed on the adjustment plate 101 to overcome an obstacle, and the mover 21 of the linear motor 20 rises, pulling up the moving plate 41 of the air spring mechanism 40, causing the internal space 47a of the dampers 47 to reach a maximum volume V3 and causing the air pressure to decrease.

[0034] At this time, the vibration test device 10 adjusts and controls the power supply to the stator 31 so as to make the up and down movement of the movable element 21 of each pair of linear motors 20 uniform and maintain the horizontal state of the adjustment plate 101, and furthermore, it is also possible to change the vibration conditions for each of the wheels W (four wheels) of the automobile C.

[0035] Therefore, by providing a pair (or multiple) of linear motors 20 as needed, the vibration test apparatus 10 does not need to prepare linear motors with unnecessarily large driving forces, and conversely, it is possible to avoid a situation where vibration cannot be applied at the desired acceleration due to insufficient driving forces. Furthermore, by providing the vibration test apparatus 10 with an air spring mechanism 40 that can easily and simply adjust the air pressure and ensures stable air pressure, it is possible to reduce the driving force required for the linear motor 20, and further, by supporting the test specimen C with the air spring mechanism 40 without requiring the driving force of the linear motor 20 before vibration, it is possible to further reduce the driving force required for the linear motor 20.

[0036] In this way, in the vibration test device 10 of this embodiment, a vibration test can be performed in which the test vehicle C is supported by the air pressure of the air spring mechanism 40 while the wheels W of the vehicle C are vibrated by the driving force of a pair of linear motors 20, and each wheel W of the heavy vehicle C can be vibrated with sufficient acceleration.

[0037] The scope of the present invention is not limited to the exemplary embodiments shown and described, but also includes all embodiments that achieve equivalent effects to those intended by the present invention. Furthermore, the scope of the present invention is not limited to the combination of inventive features specified in each claim, but can be defined by any desired combination of each and every disclosed specific feature.

[0038] DESCRIPTION OF SYMBOLS 10...Vibration test device 10F...Housing 11...Support member 20...Linear motor 21...Movers 23...Yoke 25...Magnet 31...Stator 40...Air spring mechanism 41...Moving plate 41a...Internal space 47...Damper 47a...Internal space 47v...Valve 50...Control system 51...Host control device 53...Controller 55A, 55B...Motor driver 57...Encoder 100...Vibration test system A...External air (compressed air) C...Automobile (test specimen) W...Wheel

Claims

1. A vibration testing device that applies linear vibration to a test specimen by using a linear motor that moves a movable element back and forth in a linear direction, wherein a plurality of the linear motors are installed so that their respective movable elements can reciprocate in parallel directions to vibrate a support member that supports the test specimen.

2. The vibration test device according to claim 1, wherein each of said movers of said linear motors is connected to said common support member.

3. A vibration test device according to claim 1, wherein the support member is provided with an elasticity adding mechanism that adds an elastic force that moves the movable elements of the linear motors in a direction parallel to the moving direction.

4. The vibration test device according to claim 3, further comprising an air spring mechanism as the elasticity adding mechanism.

5. The vibration test device according to claim 4, wherein the air spring mechanism is provided with a structure that makes it possible to adjust the air pressure that applies the elastic force.

6. The vibration test device described in claim 4, characterized in that the air spring mechanism has a capacity to suppress fluctuations in air pressure due to the vibration operation of the support member by the multiple linear motors, as the enclosed air that generates the air pressure that applies the elastic force.

7. The vibration test device according to claim 1, further comprising a control unit which executes a control operation for each of the plurality of movers of the linear motor so as to apply the same vibration operation to the support member.

8. A vibration test system comprising a plurality of vibration test devices according to any one of claims 1 to 7 arranged under a test specimen to carry out a vibration test on the test specimen.

9. A shock absorber testing device for automobiles, characterized in that a plurality of vibration test devices in the vibration test system described in claim 8 are arranged under the wheels of an automobile to carry out performance testing of the shock absorbers of the automobile.

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