JP3460935B2 - Electric dynamometer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric dynamometer for detecting a load using a load cell. 2. Description of the Related Art FIG. 7 is a block diagram showing a conventional electric dynamometer disclosed, for example, in Japanese Utility Model Publication No. 55-13697.
In the figure, 1 is a bearing stand fixed on the installation surface,
2 is a bearing provided on the bearing base 1 and 3 is a bearing 2
The swinging portion 3 is supported by the bearing base 1 through the shaft, and is swingable (rotatable) in both directions A and B in the drawing. Reference numeral 4 denotes a torque arm attached to the swing unit 3, and the torque arm 4 reciprocates in the C and D directions in the drawing due to the swing of the swing unit 3. A load cell 5 is fixed on an installation surface. The load cell 5 includes a metal core rod (not shown) and an electric signal provided by the core rod being distorted by a load. And a strain gauge that outputs
6 is a load receiving housing fixed on the load cell 5, 7
Reference numerals a and 7b denote a pair of load receiving seats provided in the load receiving housing 6 so as to be vertically movable in opposition to each other. Reference numeral 8 denotes a pair of load receiving seats 7a and 7b which are fixed to the distal end of the torque arm 4. The contacts 9a and 9b disposed therebetween are a pair of springs provided between the inner wall surface of the load receiving housing 6 and the load receiving seats 7a and 7b. Next, the operation will be described. For example, when the rotating side portion of the electric motor rotates in the direction B in the drawing, a force for rotating the fixed side portion in the direction A relatively acts. Therefore, a torque in the A direction or the B direction in the drawing is generated in the swinging portion 3 coupled to the fixed side portion, depending on the rotation direction of the electric motor. Thus, when the torque direction is A, a force is applied to the torque arm 4 in the C direction, and when the torque direction is B, a force in the D direction is applied to the torque arm 4. The load caused by this force is transmitted to the load cell 5 via the contact 8, the load receiving seats 7a and 7b, the springs 9a and 9b, and the load receiving housing 6, and is converted into an electric quantity by the load cell 5. Then, a torque is obtained from the electric quantity by calculation. [0006] In the conventional electric dynamometer constructed as described above, the springs 9a, 9b
In this case, since the swinging portion 3 rotates until the reaction force is balanced, an inertia torque is generated, and the generated torque cannot be accurately measured. When a force is applied to the contact 8, a reaction force acts on the swing portion 3, but the bearing 2
Is an elastic body, the bearing 2 is elastically deformed by the reaction force, and the position of the swing center of the swing portion 3 is slightly changed. That is, as the bearing 2, a rolling bearing or a static pressure bearing using hydraulic pressure is used. The rolling bearing slightly deforms elastically when a load is applied, and the static pressure bearing slightly changes the oil film thickness when the load is applied. Occurs. As a result, a moment force (which can be referred to as a frictional force because a displacement occurs in a state where a force is applied) acts on the load point of the contact 8, and the load cell 5
There is also a problem that an error occurs in the measurement value in the above, and the measurement accuracy is reduced. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reduces an inertia torque generated when the swinging portion rotates, and generates an error due to a moment force. It is an object of the present invention to obtain an electric dynamometer capable of preventing measurement and improving measurement accuracy. [0008] An electric dynamometer according to the present invention comprises: a bearing base fixed on an installation surface; a swinging part swingably supported by the bearing base; A torque arm fixed to the oscillating portion, a load cell having an upper end fixed to the torque arm and converting a load into an electric signal, a hydraulic receiving seat fixed to a lower end of the load cell, It is provided with a pair of spherical hydraulic pads provided on the installation surface facing each other above and below the seat, and a hydraulic source for applying hydraulic pressure to these spherical hydraulic pads. An embodiment of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing an electric dynamometer according to Embodiment 1 of the present invention. In the drawing, reference numeral 1 denotes a bearing base fixed on an installation surface, 2 denotes a bearing provided on the bearing base 1, and 3 denotes a swinging part supported by the bearing base 1 via the bearing 2. The oscillating part 3 is indicated by A,
B It can swing (rotate) in both directions. Reference numeral 4 denotes a torque arm attached to the swing unit 3, and the torque arm 4 reciprocates in the C and D directions in the drawing due to the swing of the swing unit 3. An upper hook 11 is fixed to the tip of the torque arm 4, a first universal joint 12 is connected to the upper hook 11, and 13 is fixed on the same mounting surface as the bearing base 1. The mounting bracket 14 is a lower hook fixed to the mounting bracket 13, and 15 is a second universal joint connected to the lower hook 14.
2, 15 are, for example, rolling bearings or sleeve bearings arranged in a cross. Reference numeral 16 denotes a load cell fixed between the first and second universal joints 12, 15, and the load cell 16 is a metal core rod (not shown).
And a strain gauge provided on the core rod and outputting an electric signal when the core rod is distorted by a load. Next, the operation will be described. When torque is generated in the swinging portion 3, a force in the direction C is applied to the torque arm 4 when the torque direction is A, and a force in the direction D is applied when the torque direction is B. The load due to this force is transmitted to the upper hook 11, the first universal joint 12, the load cell 16, the second universal joint 15, the lower hook 14, and the mounting bracket 13, and is converted into an electric quantity by the load cell 16. Then, a torque is obtained from the electric quantity by calculation. At this time, the bearing 2 undergoes an elastic deformation due to the reaction force, but the first bend freely in any direction without resistance.
In addition, by interposing the second universal joints 12 and 15, a moment force does not act on the load cell 16, and it is possible to prevent an error due to the moment force from occurring in the measured value in the load cell 16 and improve the measurement accuracy. Can be done. Further, since no moment force acts, the springs 9a and 9b (FIG. 7) conventionally used can be eliminated, and the rigidity of the components on the load cell 16 side with respect to the torque arm 4 can be increased. Further, the swing unit 3
Can be reduced, the inertia torque generated when the swing unit 3 rotates can be reduced,
This can also improve the measurement accuracy. Embodiment 2 Next, FIG. 2 is a configuration diagram showing an electric dynamometer according to Embodiment 2 of the present invention. In the figure, 16 is a load cell fixed to the tip of the torque arm 4, 17 is a U-shaped hydraulic receiving seat connected to the lower end of the load cell 16, and 18 is fixed on the same installation surface as the bearing base 1. U-shaped hydraulic receiving bracket, 19
Reference numerals a and 19b denote upper and lower spherical hydraulic pads arranged inside the hydraulic receiving bracket 18 so as to face both surfaces of the hydraulic receiving seat 17, and reference numeral 20 denotes a hydraulic source for applying hydraulic pressure to the spherical hydraulic pads 19a and 19b. is there. FIG. 3 is a plan view showing the spherical hydraulic pad 19b of FIG. 2, and FIG. 4 is a front view of FIG.
9a has a similar structure. The spherical hydraulic pad 19b has
Four hydraulic pockets 19c are provided, and oil is supplied from a hydraulic source 20 to these hydraulic pockets 19c. Therefore, the spherical hydraulic pads 19a and 19b themselves do not directly contact the hydraulic receiving seat 17, but receive the hydraulic receiving seat 17 with hydraulic pressure. Further, the spherical hydraulic pads 19a, 19
Since the bottom surface of b is spherical, the posture of the spherical hydraulic pads 19a and 19b can freely change with respect to the reaction force of hydraulic pressure. In addition, such spherical hydraulic pads 19a, 1
9b is also described in, for example, JP-A-55-72915. In such an electric dynamometer, the load applied to the torque arm 4 is reduced by the load cell 16, the hydraulic seat 17,
The power is transmitted to the spherical hydraulic pads 19 a and 19 b and the hydraulic receiving bracket 18, and is converted into an electric quantity by the load cell 16. Then, a torque is obtained from the electric quantity by calculation. At this time, the bearing 2 undergoes elastic deformation due to the reaction force, but the upper and lower spherical hydraulic pads 19a, 1
By providing 9b, no moment force acts on the load cell 16. In other words, the portion of the oil receiving seat 17 surrounded by the spherical hydraulic pads 19a, 19b draws a circular arc with the swing center roughly as the center when the swing center position of the swing portion 3 changes. Go to Therefore, if the spherical diameter is smaller than the arc, the spherical hydraulic pads 19a, 19
b follows the movement of the oil receiving seat 17 and becomes moment-free. For this reason, it is possible to prevent an error due to the moment force from occurring in the measured value in the load cell 16,
Measurement accuracy can be improved. In addition, since the moment force does not work, the load cell 1
The rigidity of the components on the sixth side can be increased. further,
Since the amount of rotation of the oscillating unit 3 can be reduced, the inertia torque generated when the oscillating unit 3 rotates can be reduced, thereby also improving the measurement accuracy. Embodiment 3 Next, FIG. 5 is a configuration diagram showing an electric dynamometer according to Embodiment 3 of the present invention. In the figure, reference numeral 21 denotes an upper mounting bracket fixed to the distal end of the torque arm 4, reference numeral 22 denotes an upper bearing mounted on the upper mounting bracket 21 via an upper fixed shaft 23, and reference numeral 24 denotes an upper portion for storing the upper bearing 22. The storage bracket 25 is a lower mounting bracket fixed on the same installation surface as the bearing base 1, 26
Is a lower bearing attached to the lower mounting bracket 25 via the lower fixed shaft 27, 28 is a lower storage bracket for storing the lower bearing 26, and 16 is connected between the upper storage bracket 24 and the lower storage bracket 28. Load cell. The lower fixed shaft 27 is disposed at right angles to the upper fixed shaft 23, so that the phases of the upper bearing 22 and the lower bearing 26 are shifted by 90 degrees. FIG. 6 is an explanatory view showing an example of the structure of the bearings 22, 26 and the storage fittings 24, 28 of FIG. In the figure, the storage brackets 24 and 28 are configured by a bearing storage box 31 and a bearing fixing bracket 32. Here, commercially available bearings have some tolerance for inclination in addition to the rotation direction, and thus are considered to have the function of a universal joint in a narrow range. In such an electric dynamometer, the load applied to the torque arm 4 is increased by the upper mounting bracket 21 and the upper fixed shaft 2.
3, upper bearing 22, upper storage bracket 24, load cell 1
6, lower storage bracket 28, lower bearing 26, lower fixed shaft 2
7 and the lower mounting bracket 25, and converted into an electric quantity by the load cell 16. Then, a torque is obtained from the electric quantity by calculation. At this time, the bearing 2 undergoes elastic deformation due to the reaction force. However, since the upper bearing 22 and the lower bearing 26 are provided, no moment force acts on the load cell 16, and the measured value in the load cell 16 shows a moment. It is possible to prevent an error due to a force from occurring, and to improve measurement accuracy. That is, when the rolling bearings as shown in FIG.
Since the outer ring may slightly fall with respect to the inner ring as shown by the arrow in the figure, the rolling bearing also functions as a universal joint within that range. In addition, since no moment force acts, the rigidity of the components can be increased. Furthermore, since the amount of rotation of the oscillating unit 3 can be reduced, the inertia torque generated when the oscillating unit 3 rotates can be reduced, and thereby the measurement accuracy can be improved. Since the bearings 22 and 26 have a gap of about 0.1 mm in the thrust direction, if the bearings are arranged in the same direction, the load cell 16 is greatly vibrated by mechanical vibration. In order to suppress such vibration, in the above example, the directions of the upper and lower bearings 22 and 26 are changed by 90 degrees. As described above, in the electric dynamometer of the present invention, the upper and lower spherical hydraulic pads are provided above and below the hydraulic receiving seat fixed to the lower part of the load cell. Therefore, no moment force acts on the load cell, and it is possible to prevent an error due to the moment force from occurring in the measured value in the load cell, thereby improving the measurement accuracy. Also,
Since no moment force acts, the rigidity of the component parts can be increased. Further, since the amount of rotation of the oscillating portion can be reduced, the inertia torque generated when the oscillating portion rotates can be reduced, thereby also improving the measurement accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing an electric dynamometer according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram showing an electric dynamometer according to a second embodiment of the present invention. FIG. 3 is a plan view showing the spherical hydraulic pad of FIG. 2; FIG. 4 is a front view of FIG. 3; FIG. 5 is a configuration diagram showing an electric dynamometer according to a third embodiment of the present invention. FIG. 6 is an explanatory view showing an example of the structure of the bearing and the storage fitting of FIG. 5; FIG. 7 is a configuration diagram illustrating an example of a conventional electric dynamometer. [Description of Signs] 1 bearing base, 3 swinging part, 4 torque arm, 12
1st universal joint, 15 second universal joint, 16 load cell, 17 hydraulic receiving seat, 19a, 19b spherical hydraulic pad, 20 hydraulic power source, 22 upper bearing, 26 lower bearing.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01L 3/16 G01L 25/00

Claims (1)

(57) [Claims] [Claim 1] A bearing base fixed on an installation surface,
A rocking portion that is rockably supported by the bearing base, a torque arm fixed to the rocking portion, a load cell having an upper end fixed to the torque arm and converting a load into an electric signal; A hydraulic receiving seat fixed to the lower end of the load cell, a pair of spherical hydraulic pads provided on the installation surface opposite to each other above and below the hydraulic receiving seat, and applying hydraulic pressure to these spherical hydraulic pads An electric dynamometer, comprising: