JP7153596B2 - Torque measuring device - Google Patents

Description

The present invention relates to a torque measuring device.

2. Description of the Related Art In recent years, in order to evaluate the performance of an automobile transmission, it is required to be able to measure the torque of the engine with high accuracy while the engine and the transmission are coupled. As a conventional torque measurement technique, there is known a torque meter that uses a drive plate provided between the crankshaft of the engine and the torque converter of the transmission (see Patent Documents 1 to 3, for example). These patent documents describe the use of strain gauges as torque detection elements.

JP-A-2005-84000 Japanese Patent No. 3669421 Japanese Patent No. 6263556

Since the drive plate is located near the engine, it is exposed to high temperatures. As the temperature of the drive plate rises, the resistance value of the strain gauge changes. Therefore, a bridge circuit using strain gauges may not be able to accurately measure torque due to the effects of high temperatures.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem, and to reduce the influence of ambient temperature on a bridge circuit and improve torque measurement accuracy.

In order to solve the above-mentioned problems, the present invention provides a measuring device for torque acting on a disk rotating body, one of which is connected to an input side rotating body and the other of which is connected to an output side rotating body, comprising: a bridge circuit arranged on the disk rotor for detecting the strain of the strain-generating portion of the disk rotor; and a temperature equalizing means having two layers, a heat layer and a heat insulation layer covering the heat transfer layer.

According to the present invention, the following effects are achieved: (1) The temperature equalizing means has a heat insulating layer, so that the influence of heat transfer and heat radiation due to the ambient temperature on the bridge circuit is reduced, and the influence of heat conduction is reduced. become dominant. Moreover, heat dissipation from the heat transfer layer covering the bridge circuit is suppressed, and the temperature uniformity of the bridge circuit is improved.
(2) Since the temperature equalizing means has a heat transfer layer, the propagation of heat energy is promoted by heat conduction, and the temperature difference between the bridge circuit components arranged at distant positions is reduced.
These maintain the zero point balance of the bridge circuit regardless of the ambient temperature.

According to the present invention, the influence of ambient temperature on the bridge circuit is reduced, and torque measurement accuracy is improved.

1 is a front view of a drive plate equipped with a torque measuring device of the present invention; FIG. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1; FIG. 2 is an enlarged view around a strain gauge in FIG. 1; 1 is a basic configuration diagram of a strain gauge bridge circuit and a block circuit diagram of a transmitter and a receiver; FIG. FIG. 4 is a connection circuit diagram of a bridge circuit of strain gauges and a temperature gauge; FIG. 4 is a temperature distribution diagram of a drive plate based on heat conduction simulation; FIG. 2 is an exploded perspective view of the temperature equalizing means of the first embodiment; It is a sectional side view of the temperature equalization means of 1st Example. FIG. 4 is an explanatory diagram of a verification test of a heat transfer layer; FIG. 10 is a cross-sectional view taken along the line XX in FIG. 9; It is a graph which drew the temperature of each temperature measurement point of a drive plate with progress, (a) shows the case before addition of a heat-transfer layer, (b) shows the case after addition of a heat-transfer layer. FIG. 4 is a graph showing the torque output error over time, where (a) shows the case before addition of the heat transfer layer, and (b) shows the case after the addition of the heat transfer layer. FIG. 8 is an exploded perspective view of the temperature equalizing means of the second embodiment; 7 is a graph showing the temperature in the vicinity of the strain gauge of the drive plate over time, where (a) shows the case where the temperature equalizing means is not provided, and (b) shows the case where the temperature equalizing means of the second embodiment is provided. . FIG. 10 is a graph showing torque output errors over time, where (a) shows the case without the temperature equalizing means, and (b) shows the case with the temperature equalizing means of the second embodiment.

In FIG. 1, a torque measuring device 1 according to the present invention is a device for measuring torque acting on a drive plate 2. As shown in FIG. The drive plate 2, as shown in FIG. 2, is a disc rotating body provided between an engine crankshaft 21 as an input side rotating body and a torque converter 22 as an output side rotating body. As shown in FIG. 1, a plurality of first bolt through holes 3 are formed around the center of the drive plate 2 around the axis O, and a plurality of second bolt through holes 4 are formed around the outer periphery. It is As shown in FIG. 2, the center of one side of the drive plate 2 abuts against the end face of the crankshaft 21 and is fastened by a first bolt 23 passing through the first bolt through hole 3. The outer peripheral portion is abutted against the torque converter 22 and fastened by the second bolt 24 passing through the second bolt through hole 4 .

As shown in FIG. 1, a ring gear 5 is formed on the outer peripheral edge of the drive plate 2 to mesh with a pinion gear of a starter motor (not shown). A centering hole 6 is formed in the center of the drive plate 2 to fit the crankshaft 21 and center the drive plate 2 . A plurality of lightening holes 7 (12 in this embodiment) are formed at equal intervals in the circumferential direction between the first bolt through hole 3 and the second bolt through hole 4 in the radial direction. . The lightening hole 7 has a substantially elliptical shape elongated in the circumferential direction.

The drive plate 2 is formed with a strain-generating portion 8 for positively generating strain when a rotational force is transmitted from the central portion on the input side to the outer peripheral portion on the output side. A plurality of strain-generating portions 8 (12 places in this embodiment) are formed at equal intervals in the circumferential direction, and are arranged between adjacent lightening holes 7 . The strain-generating portion 8 includes a rectangular thin-walled portion 10 that is elongated in the radial direction. As can be seen from FIGS. 2 and 8, the thin portion 10 is formed thin such that recesses are provided on each of the front and back sides of the drive plate 2 .

"Bridge circuit 31"
The torque measuring device 1 includes a bridge circuit 31 arranged on the drive plate 2 to detect the strain of the strain-generating portion 8 of the drive plate 2 . The bridge circuit 31 is, for example, a Wheatstone bridge circuit. In FIG. 4, the bridge circuit 31 generates a voltage between points A and B due to changes in the resistance values of the resistance elements R1 to R4, and extracts the voltage as an output voltage corresponding to the torque. Strain gauges 11 are used as the resistance elements R1 to R4. The strain gauge 11 expands and contracts due to external tensile force or compressive force, and its resistance value changes. When there is no distortion, the bridge circuit 31 is in a state of equilibrium (zero-point equilibrium) with "R1·R4=R2·R3", and the output voltage becomes zero. If the resistance value in the bridge circuit 31 varies due to the influence of temperature when there is no distortion, the zero-point equilibrium will be shifted and a so-called zero-point drift will occur. Moreover, the output sensitivity of the strain gauge 11 also changes due to the influence of temperature. The temperature equalizing means 9, which will be described later, has a function of suppressing zero-point drift of the bridge circuit 31 and change in output sensitivity of the strain gauge 11. FIG.

The output voltage between point A and point B is transmitted via a transmitter 35 having an amplifier 32, an A/D converter 33, and a CPU 34, for example. A transmitter 35 is attached to a predetermined portion of the drive plate 2 . The transmitted signal is received by a receiver 39 having a CPU 36, a D/A converter 37 and an amplifier 38, and a torque measurement value is displayed and stored by a torque output device 40. FIG. Each strain gauge 11 is configured with two resistance elements.

In FIG. 1, strain gauges 11 (indicated by 11A to 11F in FIG. 1) are attached to the front and back of the thin portion 10 . In the present embodiment, the strain gauges 11 are arranged at alternate six locations among the twelve thin-walled portions 10 . As a result, six strain gauges 11 are arranged on the same circumferential line on one side and the other side of the drive plate 2 at equal intervals. The strain gauge 11 is attached to the thin portion 10 with an adhesive or the like. As shown in FIG. 3 , the strain gauge 11 is arranged such that its central portion is positioned on a radial line L passing through the center of the thin portion 10 . FIG. 1 shows six strain gauges 11A, 11B, . Strain gauges 11G, 11H, . . . , 11L are arranged.

In FIG. 1, the torque measuring device 1 has a temperature gauge 12 (indicated by 12A to 12F in FIG. 1) that compensates for changes in the resistance value of the strain gauge 11 due to temperature, and the initial equilibrium state of the bridge circuit 31 is set to approximately zero. A zero compensation line 13 and a temperature compensation line 20 for compensating the temperature characteristics of the bridge circuit 31 are provided. Temperature gauge 12 includes a resistive element that correlates with temperature. By connecting the temperature gauge 12 with specifications matching the temperature resistance coefficient of the strain gauge 11 in series with the bridge circuit 31 as shown in FIG. It can be compensated to cancel the change and output the same voltage for the same strain.

The zero compensation line 13 and the temperature compensation line 20 are wired on one substrate. The zero compensation line 13 and the temperature compensation line 20 are connected in series to one side of the bridge circuit 31 as shown in FIG.

As shown in FIG. 1, a wiring 14 connecting the strain gauge 11, the temperature gauge 12, the zero compensation line 13 and the temperature compensation line 20 constitutes a bridge circuit 31 and is routed in a circular shape before transmission. machine 35 (not shown in FIG. 1, see FIG. 4).

FIG. 5 shows a specific example of the bridge circuit 31 of this embodiment. Reference numerals 11A1 and 11A2 denote the resistance of the strain gauge 11A in FIG. 1, and similarly, 11B1, 11B2, . 11G1, 11A1, 11K1, 11E1, 11I1, 11C1, temperature compensation line 20, zero compensation lines 13, 11L2, 11F2, 11J2, 11D2, 11H2 and 11B2 are connected in series to one branch of the bridge circuit 31. there is 11G2, 11A2, 11K2, 11E2, 11I2, 11C2, 11B1, 11H1, 11D1, 11J1, 11F1 and 11L1 are connected in series to the other branch. A voltage between point A between temperature compensation line 20 and zero compensation line 13 and point B between 11C2 and 11B1 is output as a voltage corresponding to torque. Temperature gauges 12G, 12A, 12H, 12B, 12I and 12C are connected in series between the positive power supply voltage Vcc and the bridge circuit 31, and temperature gauges 12D, 12J, 12E and 12K are connected between the bridge circuit 31 and the ground GND. , 12F and 12L are connected in series. It should be noted that the connection example described above is merely an example, and the design may be appropriately changed by routing the wiring 14 or the like.

Here, if there is a temperature difference between the temperature gauge 12 and the bridge circuit 31, the temperature difference causes a deviation in the compensation accuracy of the temperature gauge 12, and the bridge circuit 31 cannot be properly compensated. Also in the bridge circuit 31 itself, if there is a temperature difference among the strain gauges 11, the zero compensation line 13, and the temperature compensation line 20, the bridge circuit 31 will drift at its zero point. From the above, in order to improve the compensation accuracy, it is necessary to place the temperature gauge 12 and the bridge circuit 31 under substantially the same temperature.

The inventor focused on the temperature distribution based on the usage environment of the drive plate 2 and performed the following analysis. Since the drive plate 2 is arranged near the engine, it is exposed to a high temperature environment. There are three types of heat transfer: heat conduction, heat transfer, and heat radiation. 21 and torque converter 22. Focusing on heat conduction, the temperature of the crankshaft 21 is usually higher than that of the torque converter 22 of the engine. Heat is conducted radially outward from the central portion where the crankshaft 21 is connected. In other words, it was found that the temperature distribution of the drive plate 2 becomes a distribution of a radial temperature gradient in which the temperature decreases as the distance from the axis O increases, and the temperature is uniform over the entire circumference on an arbitrary circumferential line.

FIG. 6 shows the temperature distribution of the drive plate 2 by heat conduction simulation, and the range from 120° C. to 80° C. is represented by nine sections T1 to T9. T1, T2, . . . are set in descending order of temperature. From FIG. 6, it can be seen that the temperature distribution of the drive plate 2 exhibits a substantially uniform radial temperature gradient from the central portion starting from section T1 to at least section T4. The strain-generating portion 8 is formed in the range of this uniform radial temperature gradient. Regarding the sections T5 and T6, the radial distribution is disturbed by the influence of the heat radiation from the second bolt through hole 4, and around the second bolt through hole 4 there are sections T7 and T6 with low temperatures toward the second bolt through hole 4. It can be seen that T8 and T9 are distributed.

From the above, by arranging the bridge circuit 31 and the temperature gauge 12 at the same distance from the axis O, that is, the strain gauge 11, the temperature gauge 12, the zero compensation line 13, and the temperature compensation line 20 are arranged on the same side of the drive plate 2. By arranging them on the circumference, they can be placed under substantially the same temperature. In other words, if the influence of heat transfer and heat radiation can be reduced as much as possible, the temperature distribution in the drive plate 2 can be controlled mainly by the influence of heat conduction. accuracy can be improved.

In FIG. 1, the temperature gauges 12 are attached to the sides of the strain gauges 11 on one side and the other side of the drive plate 2 with an adhesive or the like. Temperature gauges 12A-12F are arranged next to the strain gauges 11A-11F on one side, and temperature gauges 12G-12L are arranged next to the strain gauges 11G-11L on the other side. In FIG. 3, reference P1 indicates the center point of the radially outer side of the strain gauge 11, and reference P2 indicates the central point of the radially inner side of the strain gauge 11. In FIG. Symbol C1 is a circumferential line around axis O passing through center point P1, and symbol C2 is a circumferential line around axis O passing through center point P2. "The strain gauge 11 and the temperature gauge 12 are arranged on the same circumference line" means that at least a part of the temperature gauge 12 is located in the range between the circumference line C1 and the circumference line C2. means In order to improve the compensation accuracy, it is preferable to arrange the temperature gauge 12 so that half or more, preferably 80% or more of the area of the temperature gauge 12 covers the range between the circumference line C1 and the circumference line C2.

The same is true for the zero compensation line 13 and the temperature compensation line 20, and "arranging the zero compensation line 13 and the temperature compensation line 20 on the same circumferential line" means that at least one of the zero compensation line 13 and the temperature compensation line 20 is arranged. It means the relation that the part is located in the range between the circumference line C1 and the circumference line C2.

"Temperature equalization means 9"
As described above, in a structure in which the bridge circuit 31 is arranged under substantially the same temperature using the temperature distribution of heat conduction, it is desirable to reduce the effects of heat transfer and heat radiation as much as possible. However, depending on the atmospheric temperature in the engine room, if there is a localized high or low temperature, local convection (heat transfer) or thermal radiation will change the resistance value of only some of the strain gauges 11, resulting in a bridge failure. A zero point drift occurs in the circuit 31 . To address this problem, the torque measuring device 1 of the present invention includes a temperature equalizing means 9 (indicated by phantom lines in FIG. 1). The temperature equalizing means 9 promotes heat conduction from the drive plate 2 and evenly transfers heat to the entire bridge circuit 31 while reducing the effects of heat transfer and heat radiation.

"First Example"
7 and 8, the temperature equalizing means 9 has at least two layers, a heat transfer layer 16 and a heat insulation layer 17. In FIG. The temperature uniformizing means 9 of the first embodiment has a three-layer structure having an insulating layer 15 in addition to a heat transfer layer 16 and a heat insulating layer 17 . The insulating layer 15 is arranged between the bridge circuit 31 and the heat transfer layer 16 . The insulating layer 15 prevents a short circuit between the bridge circuit 31 and the temperature gauge 12 due to the placement of the heat transfer layer 16 .

The insulating layer 15 covers the components of the bridge circuit 31 (the strain gauge 11, the zero compensation line 13, the temperature compensation line 20), the temperature gauge 12, and the wiring 14, which are arranged substantially on the same circumference. The front and back of 2 are arranged annularly around the axis O. The insulating layer 15 is, for example, a thin annular insulating film having a thickness of about 20 μm to 100 μm, and is adhered to the drive plate 2 with an adhesive or the like. If the strain gauge 11 or the like secures insulation by itself, the insulating layer 15 may be omitted.

As with the insulating layer 15, the heat transfer layer 16 also covers the components of the bridge circuit 31 (the strain gauge 11, the zero compensation wire 13, the temperature compensation wire 20), the temperature gauge 12 and the wiring 14, that is, the axial center The front and back of the drive plate 2 are annularly arranged around the axis O so as to overlap the bridge circuit 31 when viewed in the O direction. The heat transfer layer 16 is, for example, a thin annular plate having a thickness of about 0.2 mm to 1 mm, and is adhered to the insulating layer 15 or the drive plate 2 with an adhesive or the like.

The heat transfer layer 16 has a function of promoting heat conduction of the drive plate 2 and uniformly transferring heat to the entire bridge circuit 31 . The heat transfer layer 16 is made of a material having higher thermal conductivity than the drive plate 2 . In general, the drive plate 2 is often made of a steel plate such as SUS material or carbon steel. The thermal conductivity of SUS420J2 is about 24 W/(m·K), and the thermal conductivity of S35C is about 43 W/(m·K). The heat transfer layer 16 is made of a material having a higher thermal conductivity than these steel plates, such as copper, aluminum, brass, gold, silver, nickel, carbon, silicon, or an alloy containing any of these. It is preferably formed with Among these, it is more preferable to use copper or a copper alloy, which has an extremely high thermal conductivity of about 400 W/(m·K) and is excellent in versatility.

The heat insulating layer 17 is arranged annularly around the axis O on the front and back of the drive plate 2 so as to cover the heat transfer layer 16, that is, overlap the heat transfer layer 16 when viewed in the direction of the axis O. ing. The heat insulating layer 17 is, for example, an annular plate material having a thickness of about 0.5 mm, and is adhered to the heat transfer layer 16 with an adhesive or the like.

The thermal insulation layer 17 inhibits the effects of heat transfer and heat radiation to the bridge circuit 31 so that the effect of heat transfer dominates the temperature distribution of the drive plate 2 . Also, the heat insulating layer 17 reduces heat radiation from the heat transfer layer 16 . The heat insulating layer 17 is preferably made of a material with low thermal conductivity, such as synthetic resin, glass wool, rock wool, or cellulose fiber. Among these, foamed heat insulating materials made of synthetic resin are preferable because of their excellent versatility. The thermal conductivity of synthetic resin foam insulation is about 0.046 W/(m·K). Examples of synthetic resin foam heat insulating materials include foam polyimide heat insulating materials.

"Verification Test of Heat Transfer Layer 16"
9 is an explanatory diagram of a verification test of the heat transfer layer 16, and FIG. 10 is a cross-sectional view taken along the line XX in FIG. In FIG. 9, a metal rod 51 simulating a crankshaft of an engine is fastened by a bolt 52 to the center position of one side of the drive plate 2 . An electric heater 53 coated with silicon rubber is wound around the metal rod 51 as a heating source. The drive plate 2 is arranged in the tank 55 so that the other surface side is placed on the support portion 54 with a small contact area. The heating temperature of the electric heater 53 was set at 130°C, and the atmospheric temperature in the tank 55 was set at 80°C. According to this test, the central portion of the drive plate 2 is heated by heat conduction from the metal rod 51, and as shown in FIG. A temperature gradient occurs in which the temperature decreases as the temperature increases.

The temperature measurement points of the drive plate 2 are a temperature measurement point S1 near the center, a temperature measurement point S2 beside the wiring 14 routed in the circumferential direction, and a temperature measurement point S2 beside the strain gauge 11 and the temperature gauge 12. Three measurement points, S3, were used. Note that the temperature measurement point S1 was set at the axial end of the metal rod 51 . Also, the ambient temperature at the temperature measuring point S4 in the tank 55 was measured. At the above four temperature measurement points S1 to S4, the state before and after the addition of the heat transfer layer 16 was measured using thermocouples. The heat transfer layer 16 was an annular plate material covering the temperature measurement points S2 and S3, as indicated by the phantom lines in FIG. Specifically, a copper material having a thickness of 0.2 mm was used and attached to the drive plate 2 .

11(a) is a temperature graph before adding the heat transfer layer 16, and FIG. 11(b) is a temperature graph after the heat transfer layer 16 is added. The temperature difference V between the temperature measurement point S2 and the temperature measurement point S3, that is, the temperature difference between the position of the wire 14 and the position of the strain gauge 11 is about 10° C. before the heat transfer layer 16 is added in FIG. 11(a). On the other hand, after adding the heat transfer layer 16 in FIG.

FIG. 12 is a graph showing the torque output error from the bridge circuit 31 due to the temperature difference V over time. shows the case after the heat transfer layer 16 is added. The torque output error is about 9 Nm before the heat transfer layer 16 is added in FIG. there is Assuming that the full scale of the torque is ±1000 Nm, the addition of the heat transfer layer 16 reduces the torque output error from about 0.9% to about 0.4%.

As described above, the temperature equalizing means has at least two layers: the heat transfer layer 16 that covers the bridge circuit 31 and the heat insulation layer 17 that covers the heat transfer layer 16 and is made of a material having a higher thermal conductivity than the drive plate 2. The following effects are exhibited by setting it as the torque measuring device 1 provided with 9. FIG.
(1) Since the temperature equalizing means 9 has the heat insulation layer 17, the influence of heat transfer and heat radiation due to the ambient temperature in the engine room is reduced on the bridge circuit 31, and the influence of heat conduction becomes dominant. . Moreover, heat dissipation from the heat transfer layer 16 covering the bridge circuit 31 is suppressed, and the temperature uniformity of the bridge circuit 31 is improved.
(2) Since the temperature equalizing means 9 has the heat transfer layer 16, the propagation of thermal energy is promoted by heat conduction, and the temperature difference between the component parts of the bridge circuit 31 arranged at distant positions is reduced. be.
By these, the zero point balance of the bridge circuit 31 is maintained regardless of the ambient temperature. When the heat transfer layer 16 covers the temperature gauge 12 as in this embodiment, the compensation accuracy of the temperature gauge 12 is also maintained at a high level.

In addition, the presence of the insulating layer 15 prevents the bridge circuit 31 and the temperature gauge 12 from being short-circuited due to the provision of the heat transfer layer 16 .

"Second embodiment"
In FIG. 13, the temperature equalizing means 9 of the second embodiment is made of a material having a higher thermal conductivity than the drive plate 2 in addition to the insulating layer 15, the heat transfer layer 16 and the heat insulating layer 17 of the first embodiment. It is composed of a five-layer structure having a thermal diffusion layer 18 covering the thermal insulation layer 17 and a second thermal insulation layer 19 covering the thermal diffusion layer 18 . The insulating layer 15, the heat transfer layer 16, and the heat insulating layer 17 are the same as those in the first embodiment, so the explanation is omitted.

The heat diffusion layer 18 is annularly arranged around the axis O on the front and back of the drive plate 2 so as to cover the heat insulating layer 17 . Like the heat transfer layer 16, the heat diffusion layer 18 is a thin annular plate material of about 0.2 mm to 1 mm, and is adhered to the heat insulation layer 17 with an adhesive or the like. As with the heat transfer layer 16, the heat diffusion layer 18 is made of copper, aluminum, brass, gold, silver, nickel, carbon, silicon, or an alloy containing any of these, which have high thermal conductivity. It is preferably formed with Among these, it is more preferable to use copper or a copper alloy, which has an extremely high thermal conductivity of about 400 W/(m·K) and is excellent in versatility. The heat transfer layer 16 and the heat diffusion layer 18 may have the same shape and the same material, or may be different.

The second heat insulating layer 19 is annularly arranged around the axis O on the front and back of the drive plate 2 so as to cover the heat diffusion layer 18 . Like the heat insulating layer 17, the second heat insulating layer 19 is, for example, an annular plate material having a thickness of about 0.5 mm, and is adhered to the thermal diffusion layer 18 with an adhesive or the like. The second heat insulating layer 19 is also preferably made of a material with low thermal conductivity, such as synthetic resin, glass wool, rock wool, or cellulose fiber. Among these, foamed heat insulating materials made of synthetic resin are preferable because of their excellent versatility. The heat insulating layer 17 and the second heat insulating layer 19 may be members having the same shape and the same material, or may be different members.

"Verification test of the second embodiment"
As a verification test of the second embodiment, the drive plate 2 was tested in the case where the temperature equalization means 9 was not provided and the bridge circuit 31 was left exposed, and in the case where the temperature equalization means 9 of the second embodiment was provided. An experiment was conducted in which convective heat was applied locally with a heat gun to the portion where the temperature equalizing means 9 is arranged. The air temperature of the heat gun is 250° C. and the air velocity is 1000 m/min. A copper material having a thickness of 0.2 mm was used for each of the heat transfer layer 16 and the heat diffusion layer 18 . For the heat insulating layer 17 and the second heat insulating layer 19, foamed polyimide heat insulating material having a thickness of 0.5 mm was used.

FIG. 14 shows a temperature graph at the temperature measuring point S3 near the strain gauge 11. As shown in FIG. FIG. 14(a) is a temperature graph when the temperature equalizing means 9 is not provided, and FIG. 14(b) is a temperature graph when the temperature equalizing means 9 of the second embodiment is provided. The temperature at the temperature measurement point S3 rapidly rises to about 110° C. in FIG. 14(a). On the other hand, in FIG. 14(b) where the temperature equalizing means 9 of the second embodiment is provided, the temperature of the surface of the second heat insulating layer 19 (temperature measuring point S5) rises to nearly 200.degree. In spite of this, it can be seen that the temperature at the temperature measurement point S3 is suppressed from sudden transient changes, and the temperature rises slowly within the range of approximately 30°C to 40°C.

FIG. 15 is a graph showing the torque output error from the bridge circuit 31 caused by the temperature change at the temperature measurement point S3 over time. FIG. 15(a) shows the case where the temperature equalizing means 9 is not provided, and FIG. 15(b) shows the case where the temperature equalizing means 9 of the second embodiment is provided. The torque output error is approximately 10 Nm on the plus side and the minus side in FIG. In b), it is found to be less than 3 Nm on the plus side, which is improved to less than 0.3%.

As described above, according to the temperature uniformizing means 9 of the second embodiment, in addition to the effects (1) and (2) of the first embodiment, heat from the atmosphere is dissipated by local convection and thermal radiation. Even if energy transmission occurs partially, it is first reduced by the second heat insulating layer 19 and then diffused by the thermal diffusion layer 18 . As a result, the heat energy is uniformly reduced in the next heat insulating layer 17, so that the effects of convection (heat transfer) and heat radiation in the heat transfer layer 16 are greatly suppressed.

The preferred embodiments of the present invention have been described above. There is almost no empty space on the front and back of the drive plate 2 where the engine and the torque converter are close. Therefore, as shown in FIG. 8, the thickness t of the temperature equalizing means 9 is the three-layer structure of the first embodiment, the five-layer structure of the second embodiment, the two-layer structure without the insulating layer 15, and the four-layer structure. It is preferable to set to 3 mm or less in any of the above.

Also, if they are arranged under substantially equivalent temperatures in the temperature distribution of heat conduction, the strain gauge 11, the zero compensation line 13, the temperature compensation line 20 and the temperature gauge 12 of the bridge circuit 31 are necessarily arranged in the circumferential direction. It is not necessary, and the shape of each layer of the temperature equalizing means 9 covering them need not be limited to an annular shape.

Further, each layer of the temperature equalizing means 9 may be structured to be attached to the drive plate 2 by screwing, for example, or may be formed by coating.

The second heat insulating layer 19 is not limited to a material with low thermal conductivity, and may be a layer having a reflecting surface with a high reflectance as long as it has a heat insulating effect.

1 Torque measuring device 2 Drive plate (disc rotor)
8 strain-generating portion 9 temperature equalizing means 10 thin portion 11 strain gauge 12 temperature gauge 13 zero compensation wire 14 wiring 15 insulation layer 16 heat transfer layer 17 heat insulation layer 18 heat diffusion layer 19 second heat insulation layer 20 temperature compensation wire 21 crankshaft (input side rotor)
22 Torque converter (output side rotor)
31 Bridge circuit 51 Metal bar 52 Bolt 53 Electric heater 54 Supporting part 55 Tank S1 to S5 Temperature measurement point

Claims (7)

A device for measuring torque acting on a disc rotating body in which one of the central part and the outer peripheral part is connected to the input side rotating body and the other is connected to the output side rotating body,
a bridge circuit that is arranged on the disc rotor and detects the strain of the strain-generating portion of the disc rotor;
a temperature equalizing means having at least two layers: a heat transfer layer formed of a material having a higher thermal conductivity than the disc rotor and covering the bridge circuit, and a heat insulating layer covering the heat transfer layer;
A torque measuring device comprising: The temperature equalization means further
2. The torque measurement device according to claim 1, further comprising a heat diffusion layer formed of a material having a higher thermal conductivity than the disk rotating body and covering said heat insulation layer, and a second heat insulation layer covering said heat diffusion layer. Device. The temperature equalization means further
3. The torque measuring device according to claim 1, further comprising an insulating layer between said bridge circuit and said heat transfer layer. 2. The heat transfer layer is made of copper, aluminum, brass, gold, silver, nickel, carbon, silicon, or an alloy containing any of these. 4. The torque measuring device according to any one of claims 3 to 4. 5. The torque measuring device according to any one of claims 1 to 4, wherein the heat insulating layer is made of synthetic resin, glass wool, rock wool, or cellulose fiber. 6. The torque measuring device according to any one of claims 1 to 5, wherein the thickness of said temperature equalizing means is 3 mm or less. The disc rotating body is a drive plate having a center portion connected to a crankshaft of an engine as the input side rotating body and a torque converter connected to the outer peripheral portion as the output side rotating body. The torque measuring device according to any one of claims 1 to 6.

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