JP2001141617A - Method and apparatus for measuring contact state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for measuring the contact state of sliding faces of two sliding members quantitatively. SOLUTION: One of two members 1, 3 sliding relatively comprises means 11, 27 for radiating sound wave into one sliding member 3, means 11, 29 for receiving a reflected wave from the sliding face 9 of one sliding member 3 and a reflected wave from a reference plane 39 set on one sliding member 3 except the sliding face 9, and a reflected wave analyzing means 35 for expressing the contact state of two members 1, 3 numerically based on the relation of reflected waves from the sliding face 9 and the reference plane 39. The contact state can be expressed numerically and measured quantitatively based on the relation between the intensity of a reflected wave from the sliding face dependent on the contact state and the constant intensity of a reflected wave from the reference plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a contact state of a sliding surface of two sliding members which slide relatively to each other, and more particularly to a contact state measuring apparatus for measuring a contact state of a sliding surface by sound waves. Related to the device.

[0002]

2. Description of the Related Art Conventionally, as a means for detecting a contact state between sliding surfaces of two sliding members relatively sliding with each other, when two members are made of a conductive material, contact conduction between the two members is performed. And a method of measuring an acoustic emission waveform generated by abrasion of the sliding surface of the two members due to severe wear of the sliding surface.

[0003]

However, in the method of measuring the contact continuity between two sliding members, it is only detected that the sliding surfaces of the two sliding members located at an interval come into contact with each other. Can not do it. Further, in the method of measuring the acoustic emission waveform, it is possible to detect only an abnormal state in which the sliding surfaces of the two sliding members are severely worn and the sliding surfaces are destroyed. .

However, in an apparatus or an apparatus having a large number of sliding members, the two sliding members are already in contact with each other at the start of use, and the sliding surfaces of the two sliding members are in contact with each other. Before an abnormal state occurs and the sliding surface is destroyed, it is necessary to detect the abnormal state in advance. For this reason, it is necessary to detect the change in the contact state by quantitatively measuring the contact state between the sliding surfaces of the two sliding members.

On the other hand, it is conceivable to install a position sensor or a load sensor on the sliding surface in order to detect the contact state between the sliding surfaces of the two sliding members. However, when the sensor cannot be installed due to the shape of the sliding surface of the sliding member or the design around the sliding surface, the design of an apparatus having a sliding member for installing the sensor may be limited.

[0006] Further, as described in the Transactions of the Japan Society of Mechanical Engineers, Vol. 63, No. 611, page 2456, 1997-7, when sound waves are radiated to the sliding surfaces of two members, the sliding state depends on the contact state of the sliding surfaces. It is known that the intensity of the reflected wave of the sound wave reflected by the surface changes. However, when the roughness of the sliding surface and the movement form of the sliding surface change with the passage of time, the intensity of the reflected wave from the sliding surface changes due to these conditions. Even if the reflection intensity of the wave is compared with the reflection intensity of the reflected wave measured after performing the sliding motion for a predetermined time, it is difficult to grasp the change in the contact state.

An object of the present invention is to quantitatively measure a contact state between sliding surfaces of two sliding members.

[0008]

A contact state measuring method and a contact state measuring apparatus according to the present invention solve the above-mentioned problems by the following means. Of the two sliding members that relatively slide, a sound wave is emitted into one of the sliding members, and a reflected wave on the sliding surface of the one sliding member and the sliding of the one sliding member. The contact state between the two sliding members is measured based on the relationship with the reflected wave on the reference surface set in a portion other than the surface.

At this time, the intensity ratio between the reflected wave on the sliding surface and the reflected wave on the reference surface is calculated, and the contact state between the two sliding members is quantified by the intensity ratio.

With this configuration, the intensity ratio of the intensity of the reflected wave on the sliding surface, which varies with the pressing load of the sliding member, and the intensity of the reflected wave on the reference surface, which is always constant, is calculated. , The contact state of the two sliding members, such as the wear rate of the sliding surface, which varies with the pressing load of the sliding member,
Since the numerical value can be expressed on a relative scale without any influence from other factors that change the intensity of the reflected wave, the contact state can be quantitatively measured.

A bottomed hole having a depth approximately one-fourth of the wavelength of a sound wave having a bottom surface serving as a reference surface and an area of the bottom surface substantially equal to an area of a portion of the sliding surface on which the measured sound wave reflects is provided. Then, the state of contact between the two sliding members is quantified based on the intensity of the combined wave of the reflected wave on the sliding surface and the reflected wave on the reference surface.

In this way, in the initial state of wear,
The reflected wave from the sliding surface and the reflected wave from the reference surface are substantially in opposite phases and almost cancel each other, and the intensity of the composite wave of the two reflected waves is substantially zero or a small value. As the wear of the sliding surface progresses, the depth of the bottomed hole becomes shallower, so that the phases of the two reflected waves are shifted, and the intensity of the composite wave of the two reflected waves increases. Therefore, since the contact state can be quantified based on the intensity of the composite wave of the reflected wave on the sliding surface of the sliding member and the reflected wave on the reference surface, the contact state can be quantitatively measured.

Further, the apparatus for measuring the contact state of two sliding members by the above-mentioned contact state measuring method provides a sound wave in one of the two sliding members that relatively slide. Means for radiating sound waves, receiving means for receiving a reflected wave on the sliding surface of one of the sliding members and a reflected wave on a reference surface set at a portion other than the sliding surface of the one sliding member, and What is necessary is just to provide a device provided with reflected wave analysis means for quantifying the contact state of the two sliding members based on the relationship between the reflected wave on the surface and the reflected wave on the reference surface.

At this time, if the reference surface is the bottom surface of the bottomed hole formed in the sliding surface or the interface between the coating formed on the sliding surface and the sliding surface, The contact state can be quantified by the intensity ratio between the intensity of the reflected wave on the sliding surface, which changes with the pressing load, and the intensity of the reflected wave on the reference surface, which is always constant. At this time, the coating is formed of a material having a density different from that of the sliding member.

Further, if a waveform separating means for discriminating and separating the reflected wave on the sliding surface and the reflected wave on the reference surface based on a difference in arrival time at the receiving means is provided, the sliding surface can be easily formed on the sliding surface. This is preferable because it is possible to separate the reflected wave from the reflected wave from the reference surface.

[0016] Further, the reference surface is formed by drilling a hole in the sliding surface.
The bottom of one or more bottomed holes, the depth of which is
If the area of the bottom surface or the sum of the areas of the plurality of bottom surfaces is substantially equal to the area of the portion of the sliding surface on which the measured sound wave is reflected at approximately one-quarter of the wavelength of the measurement sound wave, the reflected wave on the sliding surface is equal to The contact state can be quantified by the intensity of the combined wave with the reflected wave on the reference surface.

Incidentally, the contact state between the sliding members of the compressor is an internal lubrication state, that is, the amount of bubbles in the lubricating oil, the change in the viscosity of the lubricating oil due to the change in the amount of refrigerant dissolved, the supply amount of the lubricating oil, etc. , And also changes due to the entry of foreign matter between the sliding members and the like. Since the contact state of the sliding member in the compressor changes over time due to such internal lubrication state and the mixing of foreign matter, it is important to quantitatively grasp the contact state of the sliding member, and to improve reliability. It is important to be able to control the operation of the compressor in accordance with the contact state between the sliding members in order to ensure the performance.

On the other hand, the operation is controlled based on any one of the contact state measuring devices described above and the contact state between the two sliding members which are relatively slid and measured by the contact state measuring device. If the compressor is provided with control means, the control unit determines in advance that the contact state of the sliding surface of the sliding member will be abnormal based on the measurement result of the contact state from the contact state measurement device. By detecting and stopping the operation of the compressor, damage to the compressor can be prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of a contact state measuring apparatus to which the present invention is applied will be described.
This will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration and operation of a contact state measuring device to which the present invention is applied. FIG. 2 is a diagram illustrating the intensity of the reflected wave at a pressing load of 100N. FIG. 3 is a diagram illustrating the intensity of the reflected wave at a pressing load of 200N. FIG. 4 is a diagram showing the relationship between the intensity ratio of the reflected wave to the pressing load and the wear rate. FIG. 5 is a cross-sectional view illustrating a schematic configuration of a compressor body including the contact state measuring device. FIG. 6 is an exploded perspective view showing a schematic configuration of an Oldham mechanism part of a compressor including the contact state measuring device, with a part thereof cut away. FIG. 7 is a cross-sectional view showing a state where the contact state measuring device is attached to the Oldham mechanism. FIG. 8 is a diagram showing a schematic configuration of the entire compressor.

As shown in FIG. 1, the contact state measuring device of this embodiment is provided for measuring a contact state between a movable sliding member 1 made of cast iron and a fixed sliding member 3. I have. The sliding member 1 reciprocates in the direction 7 along the sliding surface 5 of the sliding member 3 while being pressed against the sliding member 3 with a predetermined pressing load P. The surface 9 and the sliding surface 5 of the sliding member 3 are in contact with each other, and friction is generated by the reciprocating motion of the sliding member 1.

The contact state measuring device according to the present embodiment comprises an ultrasonic probe 11 and a contact state measurement control unit 13 and the like. The sliding surface 5 of the sliding member 3 has a bottomed hole 15 formed therein. I have. The ultrasonic probe 11 has a built-in piezoelectric element, oscillates, that is, emits and receives, a measurement sound wave, and has a tip plate 16 serving as a cover attached to a tip portion thereof. Then, an ultrasonic probe 11 for emitting and receiving a measurement sound wave is inserted into a bottomed hole 19 provided on the back surface 17 opposite to the sliding surface 5 of the sliding member 3, and
Elastic member 2 such as a spring provided on the end side opposite to 6
The elastic member 3 is elastically attached to the sliding member 3 by a fixing member 25 via the intermediate member 3. The contact state measurement control unit 13 includes an oscillation circuit 27, a reception circuit 29, an amplification circuit 31, a waveform separation circuit 3,
3, a reflection waveform analysis circuit 35, a measurement control circuit 37, and the like. The ultrasonic probe 11 and the oscillation circuit 2
7 constitutes a sound wave emitting means, and the ultrasonic probe 11 and the receiving circuit 29 constitute a receiving means.

The bottomed hole 15 is formed in the sliding surface 5 of the sliding member 3 with a depth L of 2 mm, and the bottom surface of the bottomed hole 15 is formed into a substantially planar shape to serve as a reference surface 39. ing. In addition,
The distance between the end face of the end plate 16 of the ultrasonic probe 11 and the sliding surface 5 is 10 mm, and the end plate 1 of the ultrasonic probe 11
The distance between the end face 6 and the reference plane 39 is 8 mm.
The size, that is, the area of the reference surface 39 may be smaller than the area of the end plate 16 which is the transmitting / receiving surface of the ultrasonic probe 11.
If it is half of the area of the end plate 16 which is the transmitting and receiving surface of No. 1,
Since the intensity of the reflected wave from the sliding surface 5 and the intensity of the reflected wave from the reference surface 39 are substantially the same, the measurement sensitivity is improved.

The contact state measuring device according to the present embodiment operates in response to a command 41 from the measurement control circuit 37 during measurement.
By outputting the pulse waveform 43 from the oscillation circuit 27, the ultrasonic probe 11 is vibrated, and a measurement sound wave having a frequency of 10 MHz is oscillated. The measurement sound wave is reflected by the sliding surface 5 and the reference surface 39, and each reflected wave reflected by the sliding surface 5 and the reference surface 39 is received by the ultrasonic probe 11. The received reflected wave is output as a reception signal 47 corresponding to the received reflected wave via the ultrasonic probe 11 and the receiving circuit 29 in order. The reception signal 47 is input to the waveform separation circuit 33 after being amplified to a predetermined gain by the amplification circuit 31. The received signal 47 is separated and separated by the waveform separating circuit 33 into a received signal 47a corresponding to the reflected wave from the sliding surface 5 and a received signal 47b corresponding to the reflected wave from the reference surface 37. The separated reception signals 47a and 47b are analyzed by the reflected wave analysis circuit 35 and converted into numerical values to represent the contact state. The measurement operation of the series of contact states is instructed by the measurement control circuit 37. The contact state measurement control unit 37 of the present embodiment indicates that the oscillation circuit 27 outputs a pulse waveform 43 having a frequency of 10 MHz,
Switching is performed every 1 kHz. That is, only the received signal is continuously taken in at predetermined time intervals, and the contact state is measured.

Here, a method of separating a waveform in the waveform separating circuit 33 and a method of analyzing a waveform in the reflected waveform analyzing circuit 35, that is, a numerical representation of a contact state will be described. The time difference t for receiving reflected waves from the sliding surface 5 of the sliding member 3 and the reference surface 39 which is the bottom surface of the bottomed hole 15 is, as shown in FIG.
The propagation distance difference of the measured sound wave between the sliding surface 5 and the reference surface 39 is L,
Assuming that the sound speed of the measurement sound wave is v, t = L / v (1). That is, the reflected wave from the sliding surface 5 and the reference surface 39
Is always detected with a time difference t. For this reason, each reflected wave can be easily distinguished and separated based on the time difference t. Therefore, the waveform separation circuit 33 calculates the distance from the end face of the tip plate 16 of the ultrasonic probe 11 which is input in advance to the sliding surface 5 of the sliding member 3 serving as the reflection surface of the measurement sound wave, From the distance from the end surface 16 to the reference surface 39 which is the bottom surface of the bottomed hole 15 and the sound velocity of the measured sound wave in the sliding member 3,
The arrival time of each of the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 39 is calculated, and the reception signal 47a corresponding to the reflected wave from the sliding surface 5 is calculated from each of the calculated arrival times. The received signal 47b corresponding to the reflected wave from the reference surface 39 is discriminated and separated.

On the other hand, in the physical properties related to the reflection of the ultrasonic wave propagating in the solid on the free surface, the reflectivity of the ultrasonic wave on the free surface depends on the integrated value of the speed of sound in the solid and the density of the solid. , Can be expressed by acoustic impedance. In general,
When a sound wave propagating in a solid reaches a free surface, much is reflected, and others go straight into a liquid or gas adjacent to the free surface. On the other hand, as for the phenomenon in which another solid is in contact with the surface on which the ultrasonic wave is reflected, at present, there is no basic relational expression or the like. In recent studies, as described in JSME Vol. 63, No. 611, p. 2456, 1997-7, the physical properties related to the reflection of ultrasonic waves at the contact surface between two solids are as follows. It is known that there is a close relationship with the pressure, and the transmittance of the sound wave contact surface is determined according to the contact surface pressure. The higher the contact surface pressure, the lower the ratio of reflection of ultrasonic waves at the contact surface between the two solids, and the higher the ratio of going straight. That is, the lower the contact surface pressure and the weaker the degree of contact, the higher the ratio of ultrasonic waves reflected on the contact surface, so that the intensity of the reflected wave on the contact surface increases. However, actually, in addition to the output of the oscillation circuit fluctuating with time, the roughness and the movement form of the sliding surface, which is the contact surface between the two solids, change with time in the sliding member. . Therefore, the intensity of the reflected wave from the sliding surface also changes due to fluctuations in the output of these oscillation circuits, temporal changes in the roughness of the sliding surface, the form of movement, and the like. For this reason, it is difficult to measure a contact state only by evaluating only the intensity of the reflected wave from the sliding surface.

Therefore, the reflection waveform analysis circuit 3 of the present embodiment
5 is the contact surface pressure, that is, the pressing load P of the sliding member 1
The reflected wave from the sliding surface 5 of the sliding member 3 whose strength changes due to the above, and the reference surface 39 which does not come into contact with the sliding member 1 and has a substantially constant strength regardless of the pressing load P of the sliding member 1. The contact state is measured by using the reflected wave of. The reflection waveform analysis circuit 35 determines the sliding based on the intensity An of the reflected wave from the sliding surface 5 where the intensity of the reflected wave changes depending on the contact state, and the intensity A0 of the reflected wave from the reference surface 39 which is a constant value. The intensity ratio K between the reflected wave from the surface 5 and the reflected wave from the reference surface 39
K = An / A0 (2), and the intensity of the reflected wave is normalized as the intensity ratio K. By setting the relative scale of the value of the intensity ratio K in this manner, regardless of the fluctuation of the output of the oscillation circuit or the fluctuation of the intensity of the reflected wave due to the change over time such as the roughness of the sliding surface and the movement form, The contact state can be quantified and quantitatively measured. Therefore, by quantitatively expressing the state of contact between the sliding surface 9 of the sliding member 1 and the sliding surface 5 of the sliding member 3 using the value of the strength ratio K, quantitative measurement of the contact state becomes possible. . In addition, it can be predicted in advance that the contact state between the sliding surface 9 of the sliding member 1 and the sliding surface 5 of the sliding member 3 will be abnormal from the change in the strength ratio K.

Further, in the present embodiment, in the amplification of the reception signal 47 according to the received reflected wave to a predetermined level by the amplifier circuit 31, two types of reflected waves, that is, the sliding surface 5 are used.
And the reflected wave from the reference surface 39 are simultaneously amplified. Further, as described above, the contact state is represented by the intensity ratio K of the two types of reflected waves. Therefore, the fluctuation of the amplification factor of the reception signal 47 by the amplification circuit 31 does not affect the measurement result.
Which is appropriately amplified to a level at which the intensity ratio K can be determined
C (Automatic Gain Control, automatic gain control circuit) is used.

An example of the measurement of the contact state between the two sliding members will be described below. The sliding surface 9 of the sliding member 1 is in friction with the sliding surface 5 of the sliding member 3 slightly wet with oil, and the sliding member 1 has a pressing load P100N and an amplitude 10
mm and a vibration frequency of 20 Hz. The inside of the bottomed hole 15 is the sliding surface 5 of the sliding member 3.
Wetting oil is full. At this time, as shown in FIG. 2, the primary reflected wave of the reflected wave reflected from the reference surface 39, which is the bottom surface of the bottomed hole 15, has an intensity amplitude B0 and the secondary reflected wave is smaller than the primary reflected wave. Is also observed as an attenuated waveform. The intensity of this reflected wave is constant irrespective of the sliding state and the pressing load P. The reciprocating propagation distance of the measurement sound wave reflected by the reference surface 39 is 16 mm, and the sound speed in the cast iron is 492.
Since it is 0 m / s, the reflected wave is observed 3.25 μs after the oscillation of the measurement sound wave. On the other hand, the reflected wave reflected from the sliding surface 5 is observed with a time delay, that is, a time difference t as long as the traveling distance is long. Since the reciprocating propagation distance of the measurement sound wave reflected on the sliding surface 5 is 20 mm, the primary reflection wave from the sliding surface 5 is 4.0 mm from the oscillation of the measurement sound wave.
After 7 μs, it is observed as the intensity amplitude A1 of the reflected wave. These intensities are also basically proportional to the area of the surface on which the measurement sound wave is reflected, such as the sliding surface 5 and the reference surface 39. In this measurement example, A0 has an intensity of 0.25 and A1 has an intensity of 0.65. However, since the actually measured intensity fluctuates due to the output fluctuation of the oscillation circuit 27 as described above, the value indicating the contact state is quantified as A1 / A0, that is, the intensity ratio K. The intensity ratio K at this time is
2.6.

The results are shown in the case where the pressing load P is increased to 200 N and the measurement is performed under the same conditions as above except that the friction of the sliding surface is increased. Due to the increase of the pressing load P, as shown in FIG. 3, the ratio of the measured sound wave going straight on the sliding surface 5 of the sliding member 3 increases, and the reflected wave reflected on the sliding surface 5 decreases, and as a result, the reflected wave The wave intensity becomes smaller. Therefore, the intensity A of the reflected wave from the reference surface 39
While 0 does not change, the intensity A2 of the reflected wave from the sliding surface 5 decreases. In this measurement example, A2 is equal to 0.
The intensity ratio K at this time is 1.2.
It is. As described above, the state of contact between the sliding surface 9 of the sliding member 1 and the sliding surface 5 of the sliding member 3 changes, and as the friction increases, the value of the strength ratio K decreases.

The pressing load P of the sliding member 1 is 1 to 400
An example of the result of comparing the value of the average strength ratio K at each pressing load P and the wear rate (mm / h) when changed to N is shown in FIG. As the average intensity ratio K of the reflected wave decreases due to the increase in the pressing load P of 1, the wear rate increases. Since there is a correlation between the decrease in the strength ratio K and the increase in the wear rate, by observing the value of the strength ratio K,
The change in the contact state can be detected based on the change in the wear rate. In the results shown in Figure 4, the wear rate, pressing load P is the boundary of 200 N, will rapidly increase from 10- ⁵ mm / h, the wear becomes severe abnormal state. When the pressing load P is 200 N, the strength ratio K is 1.
Therefore, by observing the value of the intensity ratio K, the intensity ratio K
It is detected in advance that as the value approaches 1, the pressing load of the sliding member 1 against the sliding member 3 approaches 200 N, resulting in an abnormal contact state in which the sliding surface 5 of the sliding member 3 becomes severely worn. can do.

Next, a scroll compressor for refrigerating or air-conditioning provided with the contact state measuring device of the present embodiment will be described as an example of an apparatus or a device including the contact state measuring device of the present embodiment. As shown in FIG. 5, the scroll compressor 49 is filled with a mixture of a refrigerant 51 and a lubricating oil 53. The refrigerant 51 is a non-chlorine HFC (Hydro
Fluorocarbon) refrigerant, and the lubricating oil 53 is a mixture of ether lubricating oil. The refrigerant is not limited to non-chlorinated HFC, but HC (Hydro Carbon) refrigerant can be used. Further, although ether lubricating oil is used as lubricating oil, ester lubricating oil can also be used.

In the scroll compressor 49, the refrigerant 51 containing the lubricating oil 53 sucked from the suction passage 55 provided in the upper cover 57 of the housing 56 of the scroll compressor 49 temporarily The oil enters a sump 61 provided at the bottom 59 of the oil tank 56. When the motor 63, which is the driving means of the scroll compressor 49 installed at the center of the housing 56, starts, the refrigerant 51 is provided at the core of the shaft 65 of the motor 63 extending in the up-down direction of the housing 56. The fluid flows through the flow path 67 and is sucked up, and enters the back pressure chamber 69 provided above the motor 63 and communicating with the flow path 67. In the back pressure chamber 69,
A wing-shaped balance weight 71 that rotates in conjunction with the shaft 65 is provided, and the rotational weight of the balance weight 71 causes the refrigerant 51 containing the lubricating oil 53 in the back pressure chamber 69.
Becomes a mist and wets the wall surface in the back pressure chamber 69.

In the back pressure chamber 69, as shown in FIG. 6, an Oldham ring 73 for converting the rotational movement of the shaft 65 into a turning movement and a wall surface in the back pressure chamber 60 are provided opposite to each other. There is an Oldham mechanism 77 including a key groove 75 and the like. The key groove 75 has a projection 76 formed by projecting from the wall surface of the back pressure chamber 69 toward the shaft 65.
Of the shaft 65 from the wall surface of the back pressure chamber 69
It is a groove formed toward the direction. At the end of the shaft 65, a column-shaped eccentric shaft portion 79 provided at a position eccentric with respect to the axis of the shaft 65 is formed. The shaft 65 and the orbiting scroll 81 are inserted into a cylindrical shaft insertion portion 83 formed at the lower portion of the orbiting scroll 81 disposed on the shaft 65.
Are linked.

On the lower surface of the Oldham ring 73, a lower surface side projection 85 inserted into the key groove 75 is formed at a position corresponding to the two key grooves 75. On the upper surface of the Oldham ring 73, an upper surface side projection 89 is formed at a position corresponding to a concave portion 87 formed at a position facing the lower surface of the orbiting scroll 81. In addition, the lower surface side protrusion 85 and the upper surface side protrusion 89 formed at the positions opposing each other on the Oldham ring 73 are alternately formed at intervals of approximately 90 degrees.
When the rotational movement of the shaft 65 is transmitted to the orbiting scroll 81, the movement of the orbiting scroll 81 is controlled by the upper side projection 89 of the Oldham ring 73 inserted into the recess 87 of the orbiting scroll 81 and the key groove 75 of the back pressure chamber 69. The orbiting scroll 81 is limited by the lower surface side projection 85 inserted into the
To prevent them from spinning.

At this time, the Oldham ring 73 is
A reciprocating motion in the direction 91 along 5 is performed. The orbiting scroll 81 is perpendicular to the direction 91 along the key groove 75 by the concave portion 87 of the orbiting scroll 81 and the upper surface side projection 89 of the Oldham ring 73 in addition to the reciprocating motion in the direction 91 along the key groove 75. A reciprocating movement in the direction 93 can also be performed. Therefore, the orbiting scroll 81 is mounted on the eccentric shaft 7.
Due to the eccentric rotation of 9, the eccentric rotation moves and the orbit moves with respect to the fixed scroll 95. As a result, a spirally formed tooth portion 97 above the orbiting scroll 81 and a spirally formed tooth portion 99 below the fixed scroll 95.
And the volume of the space formed between the teeth 97 and 99 fluctuates due to the relative movement between the teeth 97 and 99, thereby compressing the sucked refrigerant 51. While moving, it is guided to the center 101 of the orbiting scroll 81 and the fixed scroll 95. The compressed refrigerant 51 is supplied to the center 1
01 to the channel 103 formed in the fixed scroll 95
, And discharged from the discharge port 105 as a high-pressure refrigerant 51 through a discharge flow path (not shown).

In the operation of this compression process, strict reliability is required because the reciprocating Oldham ring 73
Is in contact with the key groove 75 into which the lower surface side projection 85 is inserted. The two sliding members relatively slidingly moving, that is, the projecting portion 76 formed on the wall surface of the back pressure chamber 69 and the lower surface side projection 85 of the Oldham ring 73 reciprocate in a direction perpendicular to the paper surface in FIG. The left side surface 107 of the moving lower surface side projection 85, the left side surface 109 of the key groove 75 of the projection 76, and the bottom surface 111 of the lower surface side projection 85 and the bottom surface 113 of the key groove 75 are used as sliding surfaces, respectively. Make a sliding motion. A bottomed hole 15a having a depth of 0.1 mm is formed in the bottom surface 113 of the key groove 75, and the bottom surface of the bottomed hole 15a forms a reference surface 39a. The ultrasonic probe 11a is installed on the lower surface 115 of the protrusion 76. Similarly, the left side surface 109 of the key groove 75 is
5b, a reference surface 39b is formed, and the left outer surface 117 of the projection 76 is provided with an ultrasonic probe 11b.
Is installed. The reciprocating Oldham ring 73 performs a sinusoidal motion and is stationary at both ends.
In the central part, speeds up to 0.8 m / s are reached. Further, the lower surface side projection 85 of the Oldham ring 73 is
The vertical pressure exerted on the sliding surface varies depending on the operation mode, but varies from 1 MPa to a maximum of 10 MPa.

As shown in FIG. 8, the operation control system of the scroll compressor 49 includes the ultrasonic probe 11
a, 11b, the intensity ratio K of the reflected waves received from the contact state measuring device 119 for detecting the contact state.
The abnormal state detection circuit 123 in the operation control unit 121 detects that the vehicle is approaching an abnormal state, and determines whether to continue or stop the operation, based on the value of. When the operation is stopped, the motor 63 in the scroll compressor 49 is stopped.
Command to the motor control circuit 125 for controlling the operation of
The operation of the scroll compressor 49 is stopped. At the same time, the operation control unit 121 sounds an alarm notifying that the operation of the scroll compressor 49 has been stopped.

The operation control unit 1 of the scroll compressor 49
In 21, as shown in FIG. 4, the value of the intensity ratio K of the reflected wave is larger than 1.0, the allowable wear rate is 10- ⁵ mm
/ Slower contact than h is determined to be normal, but the value of the intensity ratio K is equal to or 1.0, the allowable wear rate is 10- ⁵ m
It is determined that the state shifts to an abnormal state of not less than m / h. For example, as the wear progresses, the sliding surfaces 107 and 111 of the lower surface side projection 85 of the Oldham ring 73 are shaved and the key groove 75 is removed.
The keyway 75 of the lower surface side projection 85 of the Oldham ring 73 due to the reduction of the contact area with the sliding surfaces 109 and 113 of the Oldham ring 73
Of the Oldham ring 73 due to an increase in the pressing load P against the sliding surface, or the intrusion of foreign matter between the sliding surfaces 107 and 111 of the lower surface side projection 85 of the Oldham ring 73 and the sliding surfaces 109 and 113 of the key groove 75. For example, when the pressing load P of the lower surface side projection 85 of the Oldham ring 73 against the key groove 75 increases due to a change in the motion state, the sliding surfaces 107 and 111 of the lower surface side projection 85 of the Oldham ring 73 and the key groove 75 The friction between the sliding surfaces 109 and 113 increases. In this case, the friction is increased, the wear rate of 10- ⁵ mm /
When the value of the intensity ratio K becomes 1.0 by approaching the abnormal state of h or more, a command is issued to the motor control circuit 125, and the operation of the scroll compressor 49 is stopped.
An alarm is sounded informing that the operation of the scroll compressor 49 has been stopped. Thereby, breakage of the Oldham mechanism 77 and the like of the scroll compressor 49 can be prevented.

As described above, in the contact state measuring device of this embodiment, the reference surface 39 is formed by forming the bottomed hole 15 in the sliding surface 5 of the sliding member 3, and the fixed sliding member 3 is fixed. A measurement sound wave is oscillated from the ultrasonic probe 11 installed on the surface opposite to the sliding surface 5 of the sensor, and the reflected wave from the sliding surface 5 received by the ultrasonic probe 11 and the reference surface 3
The intensity ratio K with respect to the reflected wave from No. 9 is calculated. Sliding surface 5
The intensity of the reflected wave from
, While the reflected wave from the reference plane 39 is
Always constant. Therefore, the state of contact between the sliding surface 9 of the sliding member 1 and the sliding surface 5 of the sliding member 3 can be quantified by the intensity ratio K of the reflected wave, so that the sliding of the two sliding members is possible. The contact state of the surface can be quantitatively measured.

Further, since the strength ratio K is correlated with the wear rate of the sliding surface 5, by observing the strength ratio K, the sliding surface 9 of the sliding member 1 It is possible to detect in advance that the contact state with the surface 5 is abnormal, for example, a state in which abrasion becomes severe and breakage of the sliding surface occurs. Also, the reception signal 4 corresponding to the reflected wave from the sliding surface 5
7a and the received signal 47 corresponding to the reflected wave from the reference surface 39
b can be separated by the waveform separation circuit 33 on the basis of the time difference t between the reception times of the respective reflected waves, so that the amplification circuit 31 compares the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 39 with each other. Can be simultaneously amplified as a reception signal 47, and AGC
STC circuit (Sensitivity Time Control,
There is no need to use a complicated circuit such as a temporal sensitivity control circuit). In addition, accurate measurement of the contact state can be performed by using an amplifier circuit 31 having a simple circuit configuration such as an AGC circuit.

Further, in a compressor such as a scroll compressor 49 provided with the contact state measuring device of the present embodiment,
It is possible to detect in advance that the contact state of the sliding surface of the sliding member becomes abnormal, prevent damage to the compressor, and obtain a highly reliable refrigeration apparatus or air conditioning system. If the rate of change of the wear rate is calculated by continuously detecting the strength ratio K, the life of the sliding member can be predicted from the rate of change.

Further, in this embodiment, the inside of the bottomed hole 15 is hollow, but if the hole formed in the sliding surface becomes a problem, the bottomed hole 15 and the sliding portion 3 are provided with the density. However, it can also be filled with different metals or synthetic resins. However, the sliding member 3
The larger the difference between the material and the density in the bottomed hole 15 is, the larger the ratio of the reflection of the measurement sound wave on the reference surface 39 becomes.
The interior should be hollow, ie air. Further, in the present embodiment, one bottomed hole 15 is formed, but a plurality of holes may be formed.

In the contact state measuring device of the present embodiment, the reference surface 39 is formed by forming the bottomed hole 15 in the sliding surface 5 of the fixed sliding member 3 as shown in FIG. As shown in the figure, the surface 126 of the sliding member 3 on the fixed side and the coating film 127 formed on the surface 126 of the sliding member 3
May be used as the reference plane 129. In this case, the sliding surface 9 of the movable sliding member 1 slides on the surface of the coating film 127, and this coating film 127
Is the sliding surface 131. The measurement sound wave is reflected by a reference surface 129 which is an interface between the coating film 127 and the surface 126 of the sliding member 3 and a sliding surface 131 of the coating film 127. The contact state can be detected from the intensity ratio K of the received signals corresponding to the two reflected waves reflected by the reference surface 129 and the sliding surface 131.

For example, for the sliding member 3 made of cast iron,
A coating film 127 is formed by coating a 100 μm thick NiP film having excellent sliding resistance. The measurement sound wave is substantially as shown in FIG.
The speed of sound in 7 is 5300 m / s, which is faster than that of the sliding member 3. Accordingly, the time difference t between the reception times of the reflected wave from the reference surface 129 and the reflected wave from the sliding surface 131 is represented by the following equation (1) since the propagation distance difference L is 200 μm and the sound speed v is 5300 m / s. , 0.0377 μs. The intensity of the reflected wave from the sliding surface 131 changes with a change in the contact state, but the intensity of the reflected wave from the reference surface 129 not in contact with the sliding surface 9 of the sliding member 1 usually changes. Never. As described above, the contact state can be detected by setting the reference surface at the interface between the coating film and the sliding member without performing processing such as forming a bottomed hole in the sliding surface of the sliding member. In addition, in the case of a sliding member having a coating film formed on the surface to enhance the sliding resistance, the coating film can be used as it is, so that the number of processing steps of the sliding member for installing the contact state measuring device can be reduced. .

In this embodiment, the oscillation of the measurement sound wave and the reception of the reflected wave are performed by one ultrasonic probe 11, but an oscillator and a receiver may be separately provided. Further, the contact state measurement control unit 13 may be configured integrally with the oscillation circuit 27, the reception circuit 29, the amplification circuit 31, the waveform separation circuit 33, the reflection waveform analysis circuit 35, the measurement control circuit 37, and the like as a control panel. Alternatively, they may be configured as a set of separate units. For example, the measurement control circuit 37,
The waveform separation circuit 33, the reflected wave analysis circuit 35, and the like may be configured by one computer unit or the like.

Although the present embodiment has been described on the premise that the sliding surfaces 5 and 9 are smooth, the contact state measuring device of the present invention can be applied to a rough sliding surface and a rough sliding surface or a rough sliding surface. The present invention can also be applied in a state where the sliding surfaces are partially in contact with each other such that the surfaces slide on the smooth sliding surfaces. In this case, the intensity ratio K of the reflected wave fluctuates with time even in the same contact state. For example, the intensity ratio K is averaged at a predetermined time interval to be equal to the average intensity ratio K. For example, the average strength ratio K changes according to the change of the pressing load P over time, so that the contact state can be quantitatively measured.

(Second Embodiment) A second embodiment will be described with reference to FIGS. FIG.
It is a sectional view showing a schematic structure and operation of a contact state measuring device to which the present invention is applied. FIG. 11 is a diagram illustrating a relationship between a wear depth and a signal output according to the intensity of a composite wave.
Note that, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and the configuration and features different from those in the first embodiment will be described. FIG. 10 shows only the configuration of the sliding member different from that of the first embodiment. This embodiment differs from the first embodiment in that, as shown in FIG. 9, a plurality of sliding surfaces 5 of a fixed sliding member 3 having a depth of a quarter wavelength of a measurement sound wave are provided. Is provided with the bottomed hole 133.

Here, assuming that the amplitude a, the distance x, the wavelength λ, the time t, and the period T are generally, the intensity A of the wave is A = a · sinπ2π (x / λ−t / T)｝ ( 3) is represented by Two reflected waves from different reflecting surfaces have the same amplitude a, and the distance x from each reflecting surface is λ /
2 and assume that the reflected waves from the sliding surface and the reference surface are A
Assuming that n and A0, the equation (3) is expressed as follows: A0 + An = a · sin ｛2π (x / λ) + 2π (λ / 2 / λ)｝ = a · sin ｛2π (x / λ + /)) = a · sin ｛2π (x / λ + /)) (4) In this equation, when x = (m + 1/2) λ (5), the reflected waves from the sliding surface and the reference surface have opposite phases,
The reflected waves from the sliding surface and the reference surface cancel each other. Therefore, the depth of the bottomed hole or groove is set to approximately one quarter of the wavelength of the ultrasonic wave so that the two reflected waves have almost the opposite phases.
And, so that the intensity of the reflected wave from the sliding surface and the reference surface is equal, if the area of the portion where the measurement sound wave is reflected on the sliding surface and the reference surface is set to be equal, the sliding start state, that is, In the initial state of abrasion, the path length difference of the reflected wave becomes substantially half the wavelength, and the reflected waves from the sliding surface and the reference surface cancel each other. For this reason, the intensity of the combined wave of the reflected wave from the sliding surface and the reflected wave from the reference surface becomes substantially zero or small. If the wear of the sliding surface progresses from this initial state, and the path length difference of the reflected wave becomes shorter than half a wavelength, the waveforms of the reflected wave from the sliding surface and the reference surface deviate from the opposite phase, so that the two reflected waves The intensity of the composite wave gradually increases. Therefore, the signal output according to the intensity of the composite wave of the two reflected waves is
In the initial state of abrasion, it is almost zero or small, and as the abrasion progresses, it becomes large. Therefore, the reflected wave analyzing means of the contact state control unit (not shown) of the present embodiment determines the intensity of the composite wave of the two reflected waves. The contact state is digitized as a corresponding signal output.

When a 10 MHz ultrasonic wave is used as a measurement sound wave for the sliding member 3 made of cast iron of the present embodiment, the wavelength becomes 0.48 mm. Therefore, the sliding surface 5 to which the measurement sound wave is applied is applied to the sliding surface 5 corresponding to a quarter wavelength of the measurement sound wave.
The bottomed holes 133 having a depth of 12 mm are formed at regular intervals. Further, as described above, the interval and the number between the plurality of bottomed holes 133 are determined by the bottom surface of the plurality of bottomed holes 133, that is, the reference surface 1
The total area of 35 was set to be substantially equal to the area of the sliding surface 5 from which the measurement sound wave was reflected. Therefore, the sliding surface 5
Intensity of the reflected sound wave of the measurement sound wave reflected by the reference plane 135
Is almost equal to the intensity of the reflected wave of the measurement sound wave reflected at the. The total area of the reference surface 135 is equal to or less than half the area of the end plate 16 serving as the transmitting / receiving surface of the ultrasonic probe 11.

On the other hand, the reflected wave from the reflecting surface 5 and the reference surface 13
The reflected wave from 5 has a depth shifted by a half wavelength in the propagation direction of the wave. That is, since the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 135 have almost the same phase with the same intensity, the two reflected waves cancel each other out, and in the sliding start state, that is, in the initial state of wear. , The detection intensity of the signal output of the composite wave becomes substantially zero. Actually, since there is an error in the area of the reference plane 135 and the depth of the bottomed hole 133, it is completely zero.
There is a small output without becoming. When the sliding surface 5 is worn and the depth of the bottomed hole 133 is reduced, the phase difference between the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 135 becomes 180.
As a result, the intensity of the composite wave of the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 135 increases. In the present embodiment, FIG.
As shown in the figure, in the initial state of wear, the signal output according to the intensity of the composite wave of the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 135 is about 2.3 mV, As the wear of the surface 5 progresses and the sliding surface 5 is shaved by the wear, that is, as the wear depth increases, the depth of the bottomed hole 133 decreases and the signal output increases. The increase in signal power versus wear depth is initially linear, but tends to saturate as the wear depth increases.

As described above, in the contact state measuring device of the present embodiment, the sliding surface 5 is provided with a plurality of bottomed holes 133 having a depth of a quarter of the wavelength of the measurement sound wave, and The plurality of bottomed holes 133 are formed such that the area of the portion of the moving surface 5 where the measurement sound wave reflects is substantially equal to the area of the reference surface 135. As a result, in the initial state of wear, the reflected wave from the sliding surface 5 and the reflected wave from the reference surface 135 cancel each other, and the signal output according to the intensity of the composite wave of the received reflected wave is almost 0 or The value becomes small, and the signal output increases as the wear progresses. Therefore, the contact state can be quantified and quantitatively measured by a signal output corresponding to the intensity of the composite wave of the reflected wave from the sliding surface 5 of the sliding member 3 and the reflected wave from the reference surface 135. .

Further, in the first embodiment, the contact state between the two sliding members is quantified by the strength ratio K which is correlated with the change in the pressing load P of the sliding members. It is impossible to measure the contact state of a sliding member used under conditions where there is no change in P. But,
The contact state measuring device of the present embodiment is a sliding member used under the condition that there is no change in the pressing load P of the sliding member, although the number of processing steps is increased because a plurality of the bottomed holes 133 are formed. However, the change in the contact state can be detected. In addition, in the present embodiment, since it is not necessary to separate two reflected waves, the waveform separation circuit 33 is not required unlike the contact state measurement control unit 13 of the first embodiment, and the device configuration can be simplified.

Further, in a compressor such as the scroll compressor 49 provided with the contact state measuring device of the present embodiment, a change in the internal lubricating state such as an insufficient amount of lubricating oil or a foreign matter to the Oldham mechanism 77 is prevented. It is possible to detect in advance that the contact state is abnormal due to the degree of wear caused by increased friction of the sliding surface of the sliding member due to mixing or the like. Therefore, damage to the compressor can be prevented, and a highly reliable refrigeration apparatus and air conditioning system can be obtained.

Further, in the present embodiment, a plurality of the bottomed holes 133 are formed, but if the conditions regarding the depth of the bottomed holes and the area of the reference plane 135 are the same, the number of the bottomed holes 133 is reduced to one. You can also.

Although the sliding members 1 and 3 are made of cast iron in the first and second embodiments, the contact state measuring device of the present invention is a sliding member made of a metal other than cast iron or a synthetic resin. Can also be applied.

Further, the contact state measuring apparatus to which the present invention is applied is not limited to the scroll compressor 49 exemplified in the first embodiment, but may be a positive displacement type fluid such as a compressor, an expander, or a pump having various structures. The present invention can be applied to various machines and devices having a sliding member such as a machine and a sliding bearing.

[0057]

According to the present invention, the contact state between the sliding surfaces of the two sliding members can be quantitatively measured.

[Brief description of the drawings]

FIG. 1 shows a first example of a contact state measuring device to which the present invention is applied.
It is a figure showing a schematic structure and operation of an embodiment.

FIG. 2 is a diagram showing the intensity of a reflected wave from a sliding surface and a reflected wave from a reference surface at a pressing load of 100N of the sliding member.

FIG. 3 is a diagram showing the intensity of a reflected wave from a sliding surface and a reflected wave from a reference surface when a pressing load of the sliding member is 200N.

FIG. 4 is a diagram showing a relationship between an intensity ratio K of a reflected wave to a pressing load P and a wear rate.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a compressor main body including the contact state measuring device according to the first embodiment.

FIG. 6 is an exploded perspective view showing a schematic configuration of a compressor provided with the contact state measuring device according to the first embodiment, in which a part of an Oldham mechanism section is cut away.

FIG. 7 is a cross-sectional view illustrating a state where the contact state measuring device according to the first embodiment is attached to the Oldham mechanism.

FIG. 8 is a diagram illustrating a schematic configuration of an entire compressor including the contact state measuring device according to the first embodiment.

FIG. 9 shows a first example of a contact state measuring device to which the present invention is applied.
It is a figure showing a modification of the embodiment.

FIG. 10 is a cross-sectional view showing a schematic configuration and operation of a second embodiment of the contact state measuring device to which the present invention is applied.

FIG. 11 is a diagram showing a relationship between a wear depth and a signal output according to the intensity of a composite wave.

[Explanation of symbols]

 1,3 sliding member 5,9 sliding surface 11 ultrasonic probe 27 oscillation circuit 29 receiving circuit 35 reflected wave analysis circuit 39,135 reference plane

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Muneo Mizumoto 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. (72) Inventor Yoshitaka Fujimoto 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Hitachi Air Conditioning Systems Co., Ltd. Shimizu Production Headquarters F-term (reference) 2G024 BA30 CA02 CA13 DA12

Claims (9)

[Claims] 1. A sound wave is radiated in one of two sliding members which relatively slide and moves, and a reflected wave on a sliding surface of the one sliding member and the one of the two sliding members are compared with each other. A contact state measuring method for measuring a contact state between the two sliding members based on a relationship with a reflected wave at a reference surface set on a portion of the sliding member other than the sliding surface. 2. The method according to claim 1, wherein an intensity ratio between a reflected wave on the sliding surface and a reflected wave on the reference surface is calculated, and a contact state between the two sliding members is quantified by the intensity ratio. The method for measuring a contact state according to claim 1. 3. The depth of the sound wave having a bottom surface serving as the reference surface, which is substantially one-fourth of the wavelength of the sound wave, and the area of the bottom surface is substantially equal to the area of the sliding surface on which the measurement sound wave is reflected. Forming an equal bottomed hole, and quantifying the contact state of the two sliding members based on the intensity of the composite wave of the reflected wave on the sliding surface and the reflected wave on the reference surface. The method for measuring a contact state according to claim 1. 4. A sound wave radiating means for radiating a sound wave into one of two sliding members which relatively slide and move, and a reflected wave on a sliding surface of said one sliding member. And receiving means for receiving a reflected wave on a reference surface set on a portion of the one sliding member other than the sliding surface, based on a relationship between a reflected wave on the sliding surface and a reflected wave on the reference surface. And a reflected wave analyzing means for quantifying the contact state of the two sliding members. 5. The contact state measuring device according to claim 4, wherein the reference surface is a bottom surface of a bottomed hole formed in the sliding surface. 6. The reference surface is an interface between a coating formed on the sliding surface and the sliding surface, and the coating is formed of a material having a density different from that of the sliding member. The contact state measuring device according to claim 4, wherein: 7. The reference surface is a bottom surface of a bottomed hole formed in the sliding surface, and the depth of the bottomed hole is approximately one-fourth of the wavelength of the sound wave. 5. The contact state measuring device according to claim 4, wherein an area of the contact surface is substantially equal to an area of a portion of the sliding surface where the sound wave is reflected. 8. A method according to claim 1, wherein a plurality of said bottomed holes are formed, and a total area of a bottom surface of said plurality of bottomed holes is substantially equal to an area of a portion of said sliding surface on which said sound wave is reflected. Item 8. The contact state measuring device according to Item 7. 9. An operation is performed based on the contact state between the contact state measuring device according to any one of claims 4 to 8 and two sliding members relatively slidingly measured by the contact state measuring device. A compressor comprising control means for controlling.