JP4583622B2 - Coefficient of friction measurement device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring a friction coefficient between a belt and a pulley in a power transmission device using a belt wound around a pair of pulleys.
[0002]
[Prior art]
2. Description of the Related Art Devices that transmit a power between pulleys by winding a belt around a pair of pulleys are widely used. At this time, since the power transmission between the pulley and the belt depends on the friction force between them, it is important to know the friction coefficient between the pulley and the belt, which is one of the factors that determine the friction force. is important. An apparatus for measuring a friction coefficient of a general V-belt is described in, for example, Japanese Utility Model Laid-Open No. 5-23113.
[0003]
[Problems to be solved by the invention]
In recent years, a belt-type power transmission device in which a member having a conical surface (sheave) is arranged with the conical surfaces facing each other to form a pulley and the belt is sandwiched by the conical surface has been put into practical use. In this device, the belt wrapping radius is changed by changing the sheave interval, so that the input / output speed ratio can be changed continuously, thereby constituting a continuously variable ratio transmission (CVT). be able to.
[0004]
In such a power transmission device using a belt, it is natural that friction in the circumferential direction of the pulley responsible for power transmission is important, but it is also necessary to sufficiently consider radial friction. The radial friction affects the characteristics at the time of shifting, that is, the characteristics when changing the belt winding position, in particular, the shifting speed. In the apparatus described in the above publication, friction in the radial direction and the circumferential direction cannot be independently evaluated. Further, in the above-described conventional apparatus, it is impossible to evaluate actual driving conditions, that is, friction in a state where the belt is moving.
[0005]
The present invention has been made to solve the above-mentioned problems, and evaluates friction between a belt and a pulley used in a power transmission device independently and dynamically in the radial direction and the radial direction. With the goal.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, a measuring apparatus according to the present invention is provided with a predetermined load on a surface of the belt wound around these pulleys and contacting the pulleys between the pulleys constituting the pair. A contacting pulley was placed. This measuring pulley has surface characteristics equivalent to the surface of the original pulley of the power transmission device. Furthermore, means are provided for driving the measuring pulley, thereby generating a relative speed at the contact surface between the belt and the measuring pulley. Then, the load due to the relative speed is detected, and the friction coefficient is calculated based on the load in which the measurement pulley is in contact with the belt.
[0007]
In order to measure the friction coefficient in the circumferential direction of the original pulley of the power transmission device, the rotational speed of the measurement pulley is controlled. This generates a relative speed in the belt moving direction. And a friction coefficient can be calculated | required from the load for controlling the rotational speed of the pulley for a measurement.
[0008]
Further, in order to measure the friction coefficient in the radial direction, the measurement pulley is moved in a direction perpendicular to the belt moving direction while keeping the measurement pulley in contact with the belt. The friction coefficient can be determined from the load of this movement.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of the apparatus of this embodiment, and FIGS. 2 and 3 are diagrams showing the configuration of the main part of this embodiment. In particular, FIG. 2 is a direction in which the moving direction of the belt penetrates the paper surface. FIG. 3 is a diagram when the belt is viewed so that the moving direction of the belt is along the paper surface.
[0010]
The belt 10 is a belt-type CVT belt, has a cross-sectional shape shown in FIG. 3, and has a configuration in which a plurality of steel plates 12 having this shape are stacked and bundled with a steel band 14. ing. The belt 10 is wound around a driving pulley 16 and a driven pulley 18 corresponding to an input / output pulley for power transmission in the CVT. The drive pulley 16 is coupled to the belt drive motor 20. The driven pulley 18 is fixed on a support base 22, and the support base 22 is movable in the direction of increasing or decreasing the tension of the belt 10, that is, in the left-right direction in FIG. The support base 22 is urged in the left direction in the figure by the tension applying mechanism 26 via the load cell 24. From the indicated value of the load cell 24, the tension of the belt 10 can be calculated.
[0011]
Between the driving pulley 16 and the driven pulley 18, two measuring pulleys 28 and 30 are arranged so as to sandwich the belt 10. The measurement pulleys 28 and 30 are conical pulleys that are in contact with the side surface of the belt 10 shown in FIG. In FIG. 2, the right measurement pulley (first measurement pulley) 28 is supported by the first support column 32 and is coupled to the measurement motor 36 via the torque meter 34. A rotation speed meter 37 for detecting the rotation speed of this motor, that is, the first measurement pulley 28 is provided on the shaft of the measurement motor 36. Another measurement pulley (second measurement pulley) 30 is fixed to a slide base 38 that slides in the vertical direction in the figure, and the slide base 38 is supported by a second support column 40. The slide base 38 is connected to an actuator 44 via a load cell 42 in order to slide the slide base 38 with respect to the support column 40. Further, a linear speedometer 46 for detecting the relative speed of the slide base 38 with the second support column 40 is provided. The two support pillars 32 and 40 are slidable in the left-right direction in FIG. The gravity acting on the weights 48 and 50 urges the two support columns 32 and 40 toward each other via the levers 52 and 54.
[0012]
A back roller 56 is disposed on the outer peripheral side of the portion of the belt 10 that is sandwiched between the measurement pulleys 28 and 30 so that the belt 10 does not expand outward due to the force that the measurement pulleys 28 and 30 sandwich. ing. A belt speed meter 58 that measures the moving speed of the belt 10 is disposed at any position on the outer peripheral side of the belt 10. Since the belt 10 is configured by laminating the plates 12 as described above, the belt 10 has irregularities with a plate thickness as a period on the back surface. The belt speedometer 58 includes a pickup that detects the unevenness, and calculates the belt speed based on the detected unevenness period.
[0013]
The surfaces of the measurement pulleys 28 and 30 that are in contact with the belt 10 have the same properties as the power transmission pulley of the power transmission device in which the belt 10 is used. Specifically, the same material, surface processing, surface treatment, and lubrication conditions are the same. By evaluating the friction between the measurement pulleys 28 and 30 and the belt 10, knowledge about the friction with the pulley of the actual power transmission device can be obtained.
[0014]
Next, the evaluation concerning friction using the apparatus of this embodiment will be described. In practice, the friction coefficient is obtained to obtain the friction characteristics between the belt and the pulley.
[0015]
FIG. 4 shows a flow chart for calculating the friction coefficient in the circumferential direction of the original pulley of the power transmission device, in other words, in the moving direction of the belt 10. The belt drive motor 20 is started and the operation of the belt 10 is started (S100). The moving speed of the belt 10 is detected by a belt speedometer, and it is confirmed that the predetermined speed has been reached (S102).
[0016]
Next, adjustment is performed to eliminate slippage between the measurement pulley 28 and the belt 10 (S104). This adjustment is performed by adjusting the rotational speed of the measurement motor 36 so that the torque detected by the torque meter 34 becomes zero. As a result, the influence of the inertia of the measuring pulley 28 and the shaft coupled thereto can be eliminated. The actual contact radius of the measurement pulley is obtained from the belt speed at this time and the speed of the measurement pulley 28 detected by the tachometer 37 (S106).
[0017]
Next, measurement conditions are set (S108). The tension of the belt is applied by pulling the support base 22 leftward in FIG. 3 by the tension applying mechanism 26, and is adjusted to a predetermined value by looking at the output of the load cell 24. The lubricating oil temperature is also adjusted to a predetermined value. The slip ratio between the belt 10 and the measurement pulley 28 is adjusted using the contact radius obtained in S106, the belt speed, and the rotation speed of the measurement pulley so as to obtain a predetermined slip ratio. Preferably, the slip rate is adjusted by adjusting the rotational speed of the measuring motor 36.
[0018]
When the condition is set, the load torque acting on the measurement pulley 28 is measured by the torque meter 34 (S110). From this load torque and the aforementioned contact radius, the frictional force on the contact surface is obtained. On the other hand, the normal force acting on the contact surface is also determined from the weight of the weight 48 and the lever ratio of the lever 52. Then, by dividing the frictional force by the vertical drag, a friction coefficient in the belt moving direction (circumferential direction) can be obtained (S112).
[0019]
FIG. 5 shows a flowchart for calculating the friction coefficient in the radial direction of the original pulley of the power transmission device, in other words, in the direction orthogonal to the moving direction of the belt 10. Steps S100 and S102 shown in FIG. 5 are the same as the steps given the same reference numerals.
[0020]
After step 102 is completed, measurement conditions are set (S114). The belt tension adjustment is the same as in step S108 described above. The lubricating oil temperature is also adjusted to a predetermined value. After the measurement conditions are set, the actuator 44 is operated to move the measurement pulley 30 upward in the drawing (S116). The load required for this movement is detected by the load cell 42 (S118). Further, the moving speed is also detected by the linear speedometer 46. The normal force acting on the belt 10 and the measuring pulley 30 can be obtained from the weight of the weight 50 and the lever ratio of the lever 54, and further, in the direction (radial direction) perpendicular to the belt moving direction from this drag and the aforementioned load. A friction coefficient can be calculated (S120).
[0021]
It is also possible to detect the acceleration in the upward movement of the measurement pulley 30 in the figure and correct the load detected by the load cell 42 described above. The load detected by the load cell 42 includes, in addition to the friction between the belt 10 and the measurement pulley 30, a product obtained by multiplying the inertia force of the sliding table 38 and the portion moving with the sliding table 38, that is, mass and acceleration. For this reason, in order to eliminate this inertial force and make it possible to evaluate only the frictional force, it is possible to detect the acceleration and perform correction by this. Note that an acceleration sensor fixed to the slide base 38 can be used to detect acceleration. In addition, by using an acceleration sensor, acceleration detection accuracy can be improved as compared with the case where the acceleration is obtained by second-order differentiation of the position change.
[0022]
As described above, according to this embodiment, the friction coefficient in the radial direction and the circumferential direction of the pulley of the belt type CVT can be measured independently. It is also possible to measure the dynamic coefficient of friction, i.e. during belt rotation.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic appearance of an apparatus according to an embodiment.
FIG. 2 is a front view showing a schematic configuration of the apparatus of the present embodiment.
FIG. 3 is a side view showing a schematic configuration of the apparatus of the present embodiment.
FIG. 4 is a diagram showing a flow for obtaining a circumferential friction coefficient.
FIG. 5 is a diagram showing a flow for obtaining a friction coefficient in a radial direction.
[Explanation of symbols]
10 Belt, 28, 30 Measuring pulley, 34 Torque meter, 36 Measuring motor, 37 Tachometer, 38 Slide table, 42 Load cell, 44 Actuator, 46 Linear speedometer, 48, 50 Weight, 52, 54 Lever, 58 Belt speedometer.

Claims (5)

A power transmission device for transmitting power between the pulleys by a belt wound around a pair of pulleys, a measuring device for measuring a friction coefficient between the pulley and the belt,
In between the pulleys the pair of the belt passed around the the pulleys, in contact with the surface in contact with the pulley at a predetermined load, and measuring pulley having a surface equivalent to the surface characteristics of the pulley ,
By controlling the rotational speed of the measurement pulley, the relative speed between the belt and the measurement pulley is generated in the contact surface between the belt and the measurement pulley in the moving direction of the belt within the contact surface. First driving pulley driving means
By moving the measuring pulley in a direction perpendicular to the moving direction of the belt in the contact surface between the belt and the measuring pulley, the relative speed of the belt and the measuring pulley in the orthogonal direction is increased. A second measuring pulley driving means to be generated;
Generated by the first measuring pulley drive means, a first load detecting means for detecting a load generated in the measuring pulley by relative speed between the measuring pulleys and the belt,
Second load detection means for detecting a load generated in the measurement pulley by a relative speed between the belt and the measurement pulley generated by the second measurement pulley driving means;
First friction coefficient calculation means for calculating a friction coefficient based on the load detected by the first load detection means and the predetermined load that causes the measurement pulley to contact the belt;
Second friction coefficient calculating means for calculating a friction coefficient based on the load detected by the second load detecting means and the predetermined load for bringing the measuring pulley into contact with the belt;
A friction coefficient measuring device having The friction coefficient measuring device according to claim 1,
Each of the paired pulleys is composed of two sheaves having conical surfaces with the conical surfaces facing each other, and sandwiching the side surface of the belt with the conical surfaces facing each other,
Two measuring pulleys are provided, and these two measuring pulleys sandwich the side surface of the belt,
One of the measurement pulleys is supported on a first support column that is movable in the horizontal direction with the rotation axis of the one measurement pulley as a vertical direction,
The other measurement pulley is supported on a slide base that is slidable in the vertical direction with respect to a second support column that is movable in the horizontal direction, with the rotation axis of the other measurement pulley being in the vertical direction,
The first measurement pulley driving means is a motor that rotationally drives the one measurement pulley,
The second measurement pulley driving means is an actuator for moving the slide base in a vertical direction.
Coefficient of friction measurement device. A friction coefficient measurement apparatus according to claim 2, of the two measuring pulleys, the contact load with respect to the belt, by gravity according to the weight, the first support column and said second support column, wherein A friction coefficient measuring device that is given by energizing the belt in the direction of clamping .   4. The friction coefficient measuring apparatus according to claim 1, wherein the tension of the belt is given by a tension applying mechanism that acts to separate one of the paired pulleys from the other. In the friction coefficient measuring apparatus according to any one of claims 1 to 4 ,
The belt has a structure in which plates are laminated in the longitudinal direction of the belt and integrated with each other.
Belt speed detecting means for detecting irregularities on the outer peripheral surface of the belt and detecting a moving speed of the belt based on a period of the irregularities;
A friction coefficient measuring device having

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