JPH0643932B2 - Axle dynamometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an axle dynamometer for measuring various loads acting on an axle of an automobile.

The dynamic load that acts on the vehicle body from the road surface through the tires while the vehicle is running is very important for vehicle body design because it directly affects not only the strength calculation and safety of the vehicle but also the riding comfort of passengers and passengers. Therefore, it is desirable to be able to accurately measure various loads while the tire is rotating.

However, the load measurement in the rotating state of the wheel on which the tire is mounted cannot be measured by the idea of a simple load cell because the measurement target is a complex compound force. Furthermore, since each part of a general automobile is designed extremely rationally, there is often no room for mounting measuring devices as it is. Therefore, in order to measure the power acting on the axle of the automobile, it is necessary to remodel the object to be measured on a large scale, and it has been difficult to measure in a state close to an actual vehicle.

The object of the present invention is to measure the force acting on the axle and hence the vehicle body through the tires of a moving automobile in the stationary coordinate system as the acting force received from the ground in the state where the tires are in contact with the ground or the force received by the vehicle body. An object is to provide an axle dynamometer that can measure with high accuracy.

This object is an axle dynamometer having the structure described in the claims, that is, a connecting portion that is connected to an axle of an automobile and that is mounted with a tire and a wheel to rotate, and acts in association with rotation of the connecting portion. A detection unit for converting the component force to be converted into an electric signal, an angle signal transmitter for detecting the rotation angle of the connecting unit, and a circuit for calculating the signal representing the component force and the angle signal. Is achieved by an axle dynamometer.

According to the axle dynamometer of the present invention, the axle dynamometer can be easily attached to an automobile and no special modification is required. Therefore, the axle power in a state close to an actual vehicle can be easily and accurately measured in a short time.

Hereinafter, the present invention will be disclosed with reference to the accompanying drawings illustrating examples.

FIG. 1 shows the configuration of an axle dynamometer according to the present invention. The detection unit 1 is equipped with a detection element for measuring a necessary component force, for example, 6 component force. The 6-component force in this case is the three forces acting on each axis, as shown in FIG.
It consists of F _X , F _Y , F _Z and three moments M _X , M _Y , M _Z acting on each axis. Depending on the application, there are component forces that do not need to be measured, but here are shown in their entirety.

The detection unit 1 for measuring each of these component forces is connected to the axle to be measured and attached so as to convert the mechanical strain generated in response to each component force to be measured into an electric signal upon receiving the component force to be measured. It may consist of strain gauge connections corresponding to each stress applied. Various types of such a detecting unit 1 are known, and other configurations can be adopted. In order to take out the electric output obtained by the rotating part of the detecting part 1 to the fixed side, a slip ring 3 having an appropriate number of channels is attached. The slip ring 3 is sufficient as long as the minute output can be accurately taken out without being affected by noise and the gauge operating current can be supplied. Since there is no particular limitation, detailed description thereof will be omitted.
An angle signal transmitter 5 for converting the rotation angle of the rotating portion 2 connected to the detecting portion 1 into an accurate electric signal, for example, an encoder connected to the rotating portion of the shaft to be measured by a gear mechanism 4 is provided. The encoder as the angle signal transmitter 5 conveniently generates a reference zero signal Z and two signals A and B for determining the rotation direction. The encoder as the angle signal transmitter 5 is an example, and any resolver capable of measuring an angle or any other device capable of generating an angle signal can be similarly used.

Since the slip ring 3, the gear mechanism 4, the encoder and the like include a rotating portion, they are housed in the cover 6.
On the outside of the cover 6 in the axial direction, a pilot lamp 7 for displaying the zero position and a receptacle 8 for connecting a power source and cables for exchanging signals are attached. The cover 6 is allowed to move in the axial direction and is restrained only against rotation in the rotation direction.

Such an axle dynamometer according to the present invention has a connecting portion 9 for connecting a portion that contributes to the above-mentioned detection to the axle and further attaching a wheel integrated with a tire. The axle mounting portion 9a is configured so that it can be attached via an appropriate adapter described later so as to be able to cope with these in consideration of the dimensions of the axle, the intervals of the mounting holes, and the like. The wheel mounting portion 9b is configured so that a slightly modified wheel for measurement can be mounted.

FIG. 3 is a cross-sectional view showing a state in which the axle dynamometer according to the present invention is mounted in a measurable state, and in the figure, the axle power according to the present invention is provided through a wheel mounting hub 12 at the tip of a drive shaft 11 of an automobile. It shows a state in which the connecting portion 9 of the meter is attached. A brake disc 13 is mounted inside the wheel mounting hub 12. Some of these axles have different sizes depending on the car model, year, etc., because they have not been modified in any way. Therefore, the wheel mounting hubs 12 often have different intervals and sizes. Therefore, on the mounting hub side, there is provided a first adapter 14 which is mounted by an appropriate bolt 10 and a mounting hole which matches the first adapter, and further a mounting hole which matches the axle mounting portion 9a of the connecting portion 9. The second adapter 15, which is tightened by the bolt 16, and the second adapter 15 are interposed therebetween. As a result, the axle dynamometer according to the present invention can be attached to many vehicle types without changing the vehicle body side only by replacing at least the first adapter 14.

Further, since the axle dynamometer according to the present invention is mainly intended for power measurement in an actual state where tires are mounted,
It is necessary to install a wheel with tires attached.
Therefore, the wheel 19 that is tightened by the bolt 18 is attached to the wheel mounting portion 9b of the connecting portion 9 of the axle dynamometer via the wheel mounting adapter 17. Since the mounting hole of the wheel 19 originally matches the mounting hub 12 of the axle, some modification is required to configure this embodiment. Normally, the wheel center side is cut out to have a slightly larger diameter, and a hole that fits the wheel mounting hole of the axle dynamometer connecting portion 9 is provided. However, the modification of the wheel itself is easier and cheaper than the modification of the vehicle side. Furthermore, by preparing several types of test wheels in advance, it is not necessary to modify each time, and economical measurement and testing can be performed.

The principle of measuring the power acting on the axle using the axle dynamometer according to the present invention will be described below. Figure 4 shows
It shows a stationary coordinate showing a state in which an external force F acts on the automobile. In the figure, the running resistance direction of the automobile is vector X, the vehicle weight reaction force direction is vector Z, the acting external force is vector F, and the rotation angle of the dynamometer is θ.

FIG. 5 is a vector diagram in which the acting force F is decomposed into a dynamometer coordinate axis and a stationary coordinate system. In the figure, the acting external force F is represented by the component forces F _X and F _Z of the stationary coordinate system as follows.

F _X = F cosφ F _Z = F sinφ (1) The dynamometer coordinate axes are as follows.

F _X ′ = F cos (φ−θ) F _Z ′ = F sin (φ−θ) (2) Therefore, the following relationship is established between F _X , F _Z , F _X ′, and F _Z ′.

F _X = F _X ′ cos θ−F _Z ′ sin θ F _Z = F _X ′ sin θ + F _Z ′ cos θ (3) This relationship is the same for the moments M _X and M _Z.

When the calculation of the above formula (3) is performed in an appropriate calculation circuit,
The component force measured in the rotating coordinate system can be converted into the component force in the stationary coordinate system.

FIG. 6 is a circuit diagram showing a main part of a circuit example suitable for performing such calculation. It should be noted that the acting force may be 6-minute force, but here it is assumed that F _Y and M _Y do not rotate. Further, such an operation is not limited to the operation circuit as shown in this figure, and the same purpose can be achieved by combining a microcomputer and other configurations.

The output signal from the axle dynamometer is voltage amplified by the amplifier. On the other hand, the output signal of the encoder is converted into sin and cos through the up / down counter after phase discrimination and is multiplied by the amplifier output. The signals obtained as a result are added and calculated so as to satisfy the above expression (3).

In this way, the force acting on the axle and hence the vehicle body through the tires of the running automobile is measured in the stationary coordinate system as the acting force received from the ground in the state where the tires are in contact with the ground or the force received by the vehicle body. Is possible and the intended purpose is achieved. In addition, if the adapter is used, it becomes possible to measure the power in the state where the wheel with the tire is mounted without any special modification on the automobile body side.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of an axle dynamometer according to the present invention, FIG. 2 is an explanatory view of 6-component force, and FIG. 3 is a connection state of an axle dynamometer according to the present invention and a vehicle side. 4 is an explanatory view showing the vector direction of the external force acting on the automobile, FIG. 5 is an explanatory view showing the relationship between the rotational coordinates and the stationary coordinates, and FIG. 6 is the axle power according to the present invention. It is an example of a circuit diagram which performs signal processing of a meter. Correspondence between the main reference symbols in the figure is as follows. 1: Detection part, 2: Rotating part 3: Slip ring 4: Gear mechanism, 5: Angle signal transmitter 7: Pilot lamp 8: Receptacle 9: Connection part F: External force M: Moment

Claims (1)

[Claims] 1. A connecting part (9) which is connected to an axle of an automobile and which is rotated by mounting a tire and a wheel, and a detection for converting a component force acting with the rotation of the connecting part into an electric signal. A part (1) and an angle signal transmitter (5) for detecting the rotation angle of the connecting part (9) are provided, and the rotation angle (θ) detected by the angle signal transmitter (5) becomes zero. And an arithmetic circuit which is installed in the detection unit (1) of the signal representing the component force so as to calculate the signal representing the component force in a stationary coordinate system. Dynamometer.