Rotational transmission shaft unit, and motor and inverter test bench and EMC test facility apparatus using the same

Abstract

To provide a rotation transmission shaft unit which can effectively transmit rotation at a high-rotation number and with high torque, and is easy in installation, and to provide a transmission device for transmitting high torque / high rotation using the shaft unit, and a test device.SOLUTION: Bearings are arranged at both ends of a stiff cylinder, and a fiber-reinforced resin-made center shaft is rotatably supported by the bearings, and installation and alignment thereby become easy, thus obtaining a rotation transmission shaft unit which is enabled in high-torque / high-speed rotation. The stability of a shaft position of the center shaft can be obtained by merely supporting the stiff cylinder of the shaft unit, attachment and removal with respect to an installation position become easy due to its unitization, the alignment of a rotating machine and the shaft also becomes easy, long-span rotation transmission also becomes possible, and a high velocity of a motor test bench and an EMC test device thereby becomes possible.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotational transmission shaft unit that can effectively transmit rotation at high rotational speeds and high torques and is easy to install. The present invention also relates to a transmission device for a motor test bench using the above shaft unit, and a transmission device and a test device that transmit high torque and high rotation between mechanical rotating devices such as motors and generators existing inside and outside an anechoic chamber using the same shaft, but block electromagnetic noise. In the case of being used for a motor test bench for motor testing, a rotational transmission device with high installation accuracy that can transmit high-speed rotation and high torque between a motor and a load can be obtained. Also, in an apparatus for performing an EMC evaluation test as a component while simulating the running state of an actual vehicle in an anechoic chamber for a power electric motor and an inverter system used in an electric vehicle (EV), a hybrid vehicle (HV), a plug-in hybrid vehicle (PHEV / PHV), a fuel cell vehicle (FCV), etc., a rotational transmission mechanism suitable for use with a long span and high-speed rotation that has never existed in the past can be obtained.

Background Art

[0002] A form of rotational transmission means in which a rotating shaft is housed in a rigid tube, the rigid tube bears the thrust force and the torque reaction force, and the rotating shaft transmits only the rotational force has been well known in the field of power transmission of automobiles as a torque tube.

[0003] In such an outer rigid cylinder in an automobile torque tube, since the rigid tube bears the thrust force even in the swinging state of the suspension device, the rotational force transmission mechanism of the shaft does not need to deal with swinging, and it has the advantage of simply effectively protecting the rotating shaft. Therefore, it has been used for rotational force transmission and the like at locations accompanied by the swinging of an automobile.

[0004] However, in conventional torque tubes, although a metal shaft is inserted into a metal rigid tube, the bearings that rotatably support the shaft are located, for example, as in Patent Document 1, near the center when viewed in the longitudinal direction of the rigid tube, or, for example, as in Patent Document 2, the shaft of a rotating device to which a rotating shaft is connected rather than a metal rigid tube supports the rotating shaft, and there is no versatility as a shaft unit alone, nor is it assumed to transmit high-speed rotation such as 20,000 revolutions per minute.

[0005] The support of a conventional rotating shaft as in Patent Document 2 is such that the rotating shafts on the driving side and / or the driven side to be connected support the rotating shaft. Therefore, the centering of the rotating shaft is not guaranteed in the torque tube alone, and it depends on the shafts of the driving device and the driven device. In an apparatus such as a motor test bench that requires long-span rotation transmission, it was very difficult to center the rotation transmission shaft.

[0006] Also, since the rotating shaft was made of metal, when the distance between the bearings supporting the rotating shaft became large, a whirling phenomenon occurred, making it impossible to perform high-speed rotation such as 20,000 revolutions per minute.

[0007] Conventionally, for the EMC test of a motor for automobile drive as a field using a high-speed rotation transmission device, the test equipment (motor) was set to an operating state (standby / normal operation, etc.) and the test was carried out. However, the motor was in an idling state rather than the load state during actual automobile driving.

[0008] Also, for the EMC test of an inverter for motor control, although a motor was connected as a load, it was not a load state simulating the automobile driving state as described above.

[0009] For such conventional EMC evaluation methods, international standards CISPR 25 Edition 4:2016 (Emission Measurement) and ISO 11452-2:2019 (Immunity Test) have been formulated, and the conditions regarding the test setup have been specified. According to these, the electric motor, which is the device under test set up in the anechoic chamber, must be mechanically connected to the load motor outside the anechoic chamber.

[0010] However, when drilling a hole in the wall of the anechoic chamber and passing a high-speed rotating shaft that mechanically connects the electric motor and the load motor through the inside and outside of the anechoic chamber, the distance from the device under test (electric motor) to the tip of the radio wave absorber attached to the inner wall of the anechoic chamber is stipulated to be 1000 mm or more in the aforementioned international standards. Therefore, considering mechanical components such as radio wave absorbers and the couplings to be connected, the distance between the electric motor and the load motor is assumed to be 1500 mm or more.

[0011] When rotating at high speed using a shaft of 1000 mm or more as seen in the international standard test setup diagram, there is a risk of the shaft bouncing due to its own weight and deflection, which may cause equipment damage, but the international standard does not stipulate any special countermeasures.

[0012] Conventionally, by installing a speed reducer near the electric motor that is tested in a high-speed rotation state, the high-speed rotating shaft part is made as short as possible, and by reducing the rotational speed of the shaft side connected to the load motor to one fraction to one tenth of a few minutes, the occurrence of the shaft bouncing phenomenon has been suppressed.

[0013] However, by attaching a speed reducer between the electric motor and the load motor, its cooling system, temperature management, maintenance of mechanical parts, and measures against static electricity and electromagnetic waves are required. Furthermore, by placing the speed reducer in the middle of the shaft, uncertain factors other than the electric motor, such as the efficiency of the speed reducer, are also included in the evaluation test of the electric motor. Therefore, the evaluation must be carried out after considering these factors.

[0014] As a conventional example of the technology for weight reduction of a rotational force transmission device, there was something like Patent Document 3. In this document, as it is stated that "since there is room in the space for the rear propeller shaft 44 as described later, aiming for weight reduction and high rigidity, it is made of a hollow pipe made of carbon fiber reinforced resin (CFRP)" (paragraph number 0044), it is disclosed that in order to reduce weight and increase rigidity in the propeller shaft of an automobile, a rotational force transmission means made of CFRP is used. However, this is for the propeller shaft of an automobile and has no relevance to the EMC test of an electric motor, nor does it show the transmission of rotational force between the inside and outside of the anechoic chamber for the EMC test in terms of the required torque and rotational speed.

[0015] Patent Document 4 also discloses, in the same way, "a pipe-shaped CFRP member formed of CFRP (carbon fiber reinforced plastic), which is a lightweight and high-strength material" (paragraph number 0018) as a high-rigidity and lightweight rotational transmission shaft, but it is not for a test bench or an EMC test, nor is it a configuration in which the rotating shaft is housed in a rigid cylinder. It is just a simple shaft. Also, the use in Patent Documents 3 and 4 is not intended for the high-speed rotation from low-speed rotation to 15,000 rpm or more achieved by the present invention.

[0016] As for the prior art related to the dynamo test and EMC test of motors used in electric vehicles, etc., there is no patent document of an invention that meets the requirement of performing high-speed rotation with a long span like the above international standard.

Prior Art Documents

Patent Documents

[0017]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0018] When using a versatile rotary transmission shaft that can be used in a motor test bench or the like, the centering operation of accurately aligning the axes on the dynamo side and the motor side of the rotary shaft is very difficult. The invention of the present application aims to facilitate the centering operation in a device that performs rotary transmission between a driving side and a driven side, and also aims to enable high-speed rotation even when the span between the rotation force input side and the output side of the rotary shaft is long. Further, in a device that blocks radio waves between the driving side and the driven side, in addition to these, it is an object to be able to perform excellent radio wave shielding together with high-speed rotation and high-torque transmission.

[0019] When connecting a drive source rotating device and a driven rotating device with a rotary shaft, both the drive source and the driven rotating device are fixed to the floor, and the centering of the rotation axes of the drive source device and the driven device must be highly accurate. Therefore, the rotary shaft connecting the two, the drive source, and the driven rotating device must all be accurately centered. For this centering operation, bearings that support near both ends of the rotary shaft must be fixed to a surface plate that fixes the drive source and the driven rotating body while accurately supporting the rotary shaft.

[0020] Also, in a conventional rotary transmission mechanism using a shaft, in a case where the distance between the support bearings is a long span of, for example, 700 mm, high-speed rotation of 20,000 revolutions per minute is impossible to achieve because a skipping rope phenomenon occurs.

[0021] Furthermore, in the test of a rotating device in an anechoic chamber, a hole must be made in the wall of the anechoic chamber and a rotary shaft rotating at high speed must pass through the hole. Therefore, the shielding of the anechoic chamber against electromagnetic waves is inevitably inferior compared to the state without a hole.

[0022] Also, since there is an inverse relationship between the torque of the motor and the reduction ratio of the speed reducer, attaching the speed reducer reduces the rotational speed at the output shaft of the speed reducer but increases the torque. That is, the rotational speed of the connected load motor can be reduced to one fraction of the original, but several times the torque is required. In other words, by attaching the speed reducer, it is possible to operate the electric motor at high speed, but since the torque becomes small, it is insufficient as a test of the electric motor.

[0023] Therefore, it is desirable to use a transmission mechanism with a 1:1 rotation and torque without attaching a speed reducer. However, in the prior art, when creating a testing machine without a speed reducer, the shaft connecting the electric motor and the load motor, which are the test equipment, becomes long, and when rotating at high speed, a whirling phenomenon may occur, and the equipment may be damaged. Therefore, there is a problem of providing a rotation transmission mechanism having the performance that the torque that can be transmitted is large, the length of the shaft is long, and yet no problems occur even when rotating at high speed, and the electromagnetic noise passing through the wall of the anechoic chamber is completely blocked or suppressed as small as possible. The present invention provides a rotation transmission shaft unit, a rotation transmission mechanism, and an anechoic chamber that can solve these problems. Since the present invention solves these problems, it can simply and highly accurately provide test equipment for rotating electrical equipment such as motors under various conditions such as low-speed rotation and high torque or high-speed rotation and low torque, and can also provide a device that enables EMC testing.

Means for Solving the Problems

[0024] The invention of the present application includes the following aspects. [1] A shaft unit including a central shaft and a rigid cylinder through which the central shaft passes, the rigid cylinder having bearings at both ends for rotatably supporting the central shaft at both ends of the rigid cylinder, wherein the central shaft is made of fiber-reinforced resin, the shaft unit for transmitting rotation. [2] The shaft unit according to [1], wherein the bearing distance between both ends is 700 mm or more. [3] The shaft unit according to [2], wherein the central shaft has a bending rigidity to mass ratio that enables rotation at 20,000 revolutions per minute or more. [4] The shaft unit according to any one of [1] to [3], wherein the central shaft is made of carbon fiber reinforced resin. [5] The shaft unit according to any one of [1] to [4], wherein the central shaft unit and the rigid cylinder are conductive, and the central shaft unit and the rigid cylinder are electrically connected at both bearing positions. [6] The device according to [5], wherein the means for electrically connecting the central shaft and the rigid cylinder includes a conductor that fills the space between the central shaft and the conductive rigid cylinder. [7] A rotary transmission device between rotating machines, including the shaft unit according to any one of [1] to [6], a driving side pedestal, and a driven side pedestal, wherein the shaft unit is fixed to each of the driving side pedestal and the driven side pedestal at both ends of the rigid cylinder. [8] An anechoic chamber having the rotary transmission device according to [7].

[0025] In a test bench that requires a shaft for transmitting rotation, in a simple rotating shaft supported by bearings fixed to the floor, adjustment of the mutual positions of the two bearings is necessary, which causes difficulty in centering work. On the other hand, in a structure where the rotating shaft is supported at both ends of a rigid cylinder, that is, a so-called torque tube type shaft, by simply fixing the rigid cylinder to the floor, centering of both ends of the rotating shaft is achieved. Therefore, the inventor of the present invention conceived that by accurately positioning the rigid cylinder, centering between both the rotary drive source and the driven rotary device can be easily performed.

[0026] In addition, in order to enable high-speed rotation without the skipping rope phenomenon, the inventor of the present invention noticed that it is possible if the ratio of the bending rigidity to the mass density of the rotating shaft (in this specification, referred to as the bending rigidity to mass ratio) is such that the bending rigidity is large and yet the weight is light. And for that purpose, the inventor came up with the idea of using a shaft made of carbon fiber reinforced resin. The inventor also noticed that since the shaft made of carbon fiber reinforced resin contains carbon, the electric charge of the rotating shaft that is conducted can be immediately released to the ground potential via the metal bearing. Furthermore, the inventor came up with the idea that although the shaft and the conductive rigid cylinder covering it, for example, a metal rigid cylinder cover, penetrate the wall of the anechoic chamber, high-frequency waves can be shielded by surrounding the circumference of the shaft surface with conductive fibers electrically connected to the metal cover.

[0027] The skipping rope phenomenon is impossible to prevent when using a metal shaft in the case of a bearing span exceeding 700 mm.

[0028] In the present invention, the torque capacity of the load motor is utilized to the maximum without using a speed reducer. Since no speed reducer is used, the distance between the electric motor as the test equipment and the load motor outside the anechoic chamber becomes long. However, since a shaft made of carbon fiber reinforced resin is used, it becomes lightweight and highly rigid, and no problems occur even from low-speed rotation to high-speed rotation.

[0029] In this specification, the term "conductive rigid cylinder" refers to materials having the conductivity of metals such as aluminum, iron, copper, brass, etc., that is, materials having a volume resistivity of 2x10-8 Ωm to 100x10-8 Ωm at room temperature, which is referred to as conductivity, and the term "rigid body" also means having the degree of rigidity possessed by these metals. In addition, the term "test bench" means equipment that connects a rotational force drive source fixed to the floor and a driven rotating device fixed to the same floor to perform some tests such as an output test of the rotational drive source and a radio wave test in a rotating state. Furthermore, the term "shaft length" refers to the distance between the bearings at both ends of the rigid cylinder.

[0030] The conductive rigid cylinder is most preferably cylindrical, but since it is a rigid body, it suffices as long as the position of the conductive rigid cylinder does not change. Therefore, if the rigid cylinder is fixed to the floor of the equipment installation location, the support position of the rotating shaft is fixed, and sufficient stabilization of the rotation axis position of the rotating shaft for centering the rotating shaft can be obtained. If it is fixed to the installation location floor at positions close to both ends of the conductive rigid cylinder, the positioning of the bearing with respect to the installation location floor becomes even stronger than the positioning depending on the rigidity of the rigid cylinder, and the bearing positioning of the rotating shaft becomes the most accurate. This floor may be a surface plate so that the relative positions of both ends of the rotating shaft are determined and immovable. In addition, since the conductive rigid cylinder serving as the housing of the rotating shaft is a rigid body, the positional variation during operation at the joint with the wall in the case of penetrating the wall is also extremely small.

[0031] A shaft rotating at high speed is shielded by a shield box which is a conductive rigid cylinder, and the rotating shaft is supported by using metal bearings at both ends of the shield box, and the effect of grounding can be aimed at. Furthermore, conductive resin brushes are brought into contact with the periphery of the shaft at both ends of the shield box, and the shielding effect is improved by closing the space. The shield box is conductive and is also electrically connected to the electromagnetic shielding wall, and electromagnetic shielding is maintained.

Advantages of the Invention

[0032] In the shaft unit of the present invention, since the rigid cylinder rotatably supports the rotating shaft by bearings at both ends of the cylinder, the positioning of the rotation axis of the rotating shaft is ensured by the composite cylinder, and there is no need to align the rotating shaft with the rotation axis of the rotating equipment to which the rotating shaft is connected. Further, since the rotating shaft supported by the rigid cylinder and the bearings at both ends thereof is made of fiber-reinforced resin, even if the rigid cylinder is extremely long compared to the prior art, the occurrence of the skipping phenomenon is prevented, and there is an effect that high-speed rotation of 20,000 revolutions per minute or more is possible. Therefore, even if the distance between two rotating devices that perform rotational transmission by the shaft is long, there is an effect that it is possible to transmit high-speed rotation.

[0033] Further, in the shaft unit of the present invention, since the rigid cylinder of the unit guarantees the axial position accuracy of the rotating shaft, even if the required accuracy of the installation positioning of the drive source and the load for which the shaft unit performs rotational transmission is lowered, the positioning accuracy in the shaft unit is guaranteed by the rigid cylinder, so that positioning capable of high-speed rotation can be easily executed. That is, if the positioning of the rigid cylinder of the unit is executed, the spatial positioning of the rotary support bearing of the rotating shaft at the installation position is executed, so that the alignment of the rotating shaft is simple.

[0034] Since the conductive rigid cylinder is a rigid body, the bearing positioning of the rotating shaft is accurate, and there is an effect of preventing skipping. Further, since the conductive rigid cylinder that serves as the housing of the rotating shaft is a rigid body, the positional variation during operation at the joint with the wall in the case of penetrating the wall is also extremely small.

[0035] The rotating shaft is made of fiber-reinforced resin and has a sufficiently high bending rigidity with respect to the mass. Therefore, even if the distance between the bearings at both ends of the rigid cylinder is 700 mm or more, there is an effect that the skipping phenomenon does not occur during high-speed rotation. As the fiber-reinforced resin, carbon fiber-reinforced resin or aramid fiber-reinforced resin is optimal. And if carbon fiber is used, it is also optimal for the EMC test apparatus using the anechoic chamber described later.

[0036] In the case of an anechoic chamber using the shaft unit of the present invention, a wide range of torques from low torque to high torque required for EMC tests and high-speed rotations from low speeds of several tens of revolutions per minute to high speeds of tens of thousands of revolutions per minute can be realized, enabling EMC tests defined by international standards. By making the shaft of carbon fiber reinforced resin, it becomes possible to suppress the occurrence of the skipping rope phenomenon. Therefore, it becomes possible to transmit higher torque and higher speed rotation than before. For example, it is possible to achieve 20,000 revolutions per minute and a transmission torque of 350 Nm, whether the shaft length is 900 mm or more than that.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0038] Fig. 1 is an example of the shaft unit of the present invention. The central shaft 1 for transmitting rotation is made of fiber-reinforced resin. This central shaft 1 penetrates the rigid cylinder 2 in the axial direction of the rigid cylinder 2 having rigidity, and at both ends of the rigid cylinder 2, it is rotatably supported by bearings 3. The rigid cylinder 2 can also have a bearing distance of 700 mm or more, and the bearing distance may be 1400 mm. In order to realize a lightweight and high-speed rotation-resistant rotating shaft, the shaft 1 is preferably a hollow shaft made of carbon fiber reinforced resin.

[0039] The rigid cylinder 2 is preferably made of cylindrical metal and has a thickness that does not cause resonance or deformation even during high-speed rotation such as 20,000 revolutions per minute. In addition, in the shaft unit of the present invention in which the central shaft 1 and the rigid cylinder 2 are combined via the bearing 3, as long as the rigid cylinder 2 of the shaft unit is firmly installed, the positioning of the bearing 3, which is the support point of the rotating shaft, is achieved. Therefore, it is not necessary to ensure the positioning accuracy of the rotation axis of the central shaft on the driving side and the driven side of the rotational transmission, and the shaft unit can be used for various purposes.

[0040] Figure 2 shows an example of a motor test bench equipped with the shaft unit of the present invention. For example, a motor 4 as a driving-side rotator applies a rotational force to the central shaft 1 via some kind of rotational transmission joint, and the rotational force is transmitted by the central shaft 1 to the dynamo 6 as a load-side rotator via some kind of rotational transmission joint with the central shaft 1 as well. The motor 4 and the dynamo 6 are fixed to the strong installation bases 7 and 8, but the rotatable support of the central shaft 1 is performed by the bearings 3 provided at both ends of the rigid cylinder 2, and the rigid cylinder 2 is installed and fixed to the installation base 5. Since the alignment accuracy of the rotation axis of the central shaft is achieved by the bearing 3 and the rigid cylinder 2, on the side of the motor 4 and the dynamo 6, more degrees of freedom of the rotational transmission joint can be obtained. In addition, since the central shaft and the rigid cylinder 2 can be made the support bases of the motor 4 and the dynamo 6, it is possible to block the vibration caused by the motor 4 and the dynamo 6.

[0041] Figure 3 shows a cross-sectional view of the shield room wall at the shaft penetration position of an electromagnetic shield room that can be used for EMC tests and the like, equipped with the shaft unit of the present invention. For electromagnetic shielding, an electromagnetic shield brush 9 is provided immediately outside the bearing of the rigid cylinder 2. Also in Figure 3, similar to Figure 2, if the driving rotator is located on the left side of the figure and the load rotator is located on the right side, and the inside of the shield room is on the left side of Figure 3, then the right side of the shield wall 10 is outside the shield room. The shielding wall 10 is electromagnetically shielded by directly contacting with the rigid cylinder 2 so as to be electrically conductive, contacting through a conductive flexible substance such as a metal mesh, connecting a flexible metal bellows to the shielding wall and the conductive rigid cylinder 2, etc.

[0042] The conductive rigid cylinder 2 is joined to the shielding wall 3 and may be fixed to the floor on which the device is installed via an installation base 5, for example, near both ends, but it does not necessarily have to be fixed at both end positions.

[0043] The central shaft 1 is made of carbon fiber reinforced resin, and the central shaft and the conductive rigid cylinder 2 are electrically connected to each other by bearings 3 and conductive brushes 9. The conductive brush fills the gap between the entire circumference of the central shaft and the conductive rigid cylinder 2 with a density sufficient to sufficiently shield electromagnetic waves of a desired frequency. Leakage of current or electromagnetic waves from one side of the wall to the other side is prevented because the current does not enter through the conductive shaft and escapes from the housing 2 to the wall via the conduction means between the rotating shaft and the housing 2. The shielding wall and the conductive housing do not have to be completely sealed as long as the electromagnetic wave leakage is sufficiently small. This anechoic chamber is a suitable anechoic chamber for use in, for example, EMC tests of electric motors for electric vehicles.

[0044] The conductive brush 9 may be a metal brush.

[0045] The anechoic chamber using the rotation transmission mechanism according to the present invention enables a test to be performed by transmitting a rotation motion with a high torque and high speed rotation as described above while maintaining electromagnetic shielding properties. Therefore, the anechoic chamber for EMC test using this enables a test at a high speed rotation that has never existed before.

[0046] The anechoic chamber according to the present invention can effectively block radio waves of 9 kHz to several GHz required in EMC tests.

Explanation of reference numerals

[0047] 1 Central shaft 2 Rigid cylinder 3 Bearing 4 Driving rotary machine 5 Shaft unit support base 6 Load rotary machine 7 Driving side base 8 Load side base 9 Electromagnetic shield brush 10 Shield wall

Claims

1. A shaft unit for a motor and / or generator test bench or for their EMC tests, comprising a central shaft and a rigid cylinder through which the central shaft passes, the rigid cylinder having bearings at both ends for rotatably supporting the central shaft at both ends, wherein the central shaft is a single-piece shaft made of fiber-reinforced resin without additives in the portion between the bearings, and transmits a rotational force from a driving device outside the bearing at one end to a driven device outside the bearing at the other end, the distance between the bearings at both ends being 700 mm or more and 1400 mm or less, and the central shaft having a bending rigidity to mass ratio that allows it to rotate at 20,000 revolutions per minute or more and 60,000 revolutions per minute or less.

2. The shaft unit according to claim 1, wherein the central shaft is made of carbon fiber-reinforced resin or aramid fiber-reinforced resin.

3. The shaft unit according to claim 1 or 2, wherein the central shaft and the rigid cylinder are conductive, and the central shaft and the rigid cylinder are electrically connected at the positions of the bearings at both ends.

4. The shaft unit according to claim 3, wherein the means for electrically connecting the central shaft and the rigid cylinder includes a conductor that fills the space between the central shaft and the conductive rigid cylinder.

5. A rotation transmission device having the shaft unit according to any one of claims 1 to 4, wherein the shaft unit is fixed to a driving side mount and a driven side mount at both ends of the rigid cylinder, respectively.

6. An anechoic chamber having the shaft unit according to any one of claims 1 to 4, the anechoic chamber having the shaft unit for transmitting a rotational force between the inside and outside of the anechoic chamber.

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