JPH0425730A - Fixation fitting structure for rotary torque detecting device - Google Patents

Abstract

PURPOSE:To accurately control an output from a driving side by forming a means which clamps and fixes the external fitting part of a displacement-direction converting means to a shaft by using a material which is lower in coefficient of heat expansion than the displacement-direction converting means. CONSTITUTION:Expansible bodies 5a and 5b of the torque sensor 5 of the device are formed of synthetic resin and a driving shaft 1, a driven shaft 2, and clamping nut 12 and 20 are formed of iron which is lower in coefficient of heat expansion than the expansible bodies 5a and 5b. The shaft mount parts 9 and 17 of the expansible bodies 5a and 5b which expand at high temperature more than the driving shaft 1 and driven shaft 2 are pressed by the clamping nuts 12 and 20, so that the expansible bodies 5a and 5b have no play on both the shafts 1 and 2. If the temperature drops in this state, the inner peripheral surfaces of the expansible bodies 5a and 5b only press the outer peripheral surfaces of the fitting parts 10 and 18 of the driving shaft 1 and driven shaft 2 respectively. Then the shaft mount parts 9 and 17 of the expansible bodies 5a and 5b are fixed and held on the driving shaft 1 and driven shaft 2. The sensor 5 has no play on both the shafts 1 and 2 regardless of temperature variation and the output is accurately controlled from the driving shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fixed mounting structure of a rotational torque detection device.

[Prior Art] The following rotary torque detectors are used in power steering devices of industrial vehicles.

That is, as shown in FIG. 6, the torque sensor that connects the flange portions 39 of the drive shaft A and the driven shaft F consists of a pair of resin rings 40 made of a highly flexible synthetic resin material. The resin ring 4o is formed by connecting a shaft mounting part 41 and a bobbin mounting part 42 with an oblique mounting arm 43.

The bobbin attachment parts 42 of both resin rings 40 are connected by a bobbin 44, and the ends of both shafts A and F are made to face each other within both resin rings 40 and the bobbin 44.

A solenoid coil 46 is wound on the bobbin 44, and a capacitor 47 is connected to the solenoid coil 46. Further, a copper ring 48 is fitted onto the outer peripheral surface of the drive shaft A within the bobbin 44, and the coil 46, the capacitor 47, and the copper ring 48 constitute a resonant coil.

The copper ring 48 is always close to the inner surface of the bobbin 44 at a position close to the coil 46, and as the resin ring 40 expands and contracts, the inductance of the resonance cycle is increased or decreased by the displacement of the solenoid coil 46 as the position of the bobbin 44 changes. Then, in a detection circuit (not shown), when this increase/decrease in inductance is detected as a change in frequency, it is converted into a voltage signal by an f/V converter connected to the detection circuit, and based on this voltage value, the drive shaft A The drive source is controlled in i-control.

[Problems to be Solved by the Invention] However, the above-mentioned torque sensor is often installed in a part of the frame where the temperature rises rapidly, such as in the steering mechanism of an industrial vehicle. The resin ring 40 has both axes A
, F has a larger coefficient of thermal expansion than F, so the diameters of the shaft attachment part 43 of the resin ring 40 and both shafts AF change unevenly, causing the resin ring 40 to wobble and cause a slight deviation in the output from the drive shaft A to the torque sensor. As a result, the drive source of the drive shaft A may not be controlled accurately.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a rotational torque sensor that can accurately control the output from the drive side.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is provided with a shaft that is fitted on the outside of a shaft that transmits power to a driving side and a driven side, and that moves in the axial direction according to displacement of the shaft in the rotational direction. A rotation device in which a displacement direction converting means for elastically displacing is formed of a material having a coefficient of thermal expansion higher than that of the shaft, and a conversion/extraction means for converting the displacement in the axial direction of the displacement direction converting means into an electric signal and taking out the electric signal. In the torque detection device, the tightening fixing means for fixing the external fitting portion of the displacement direction converting means to the shaft is formed of a material having a lower coefficient of thermal expansion than the displacement direction converting means. This is the summary.

[The outer fitting part of the displacement direction converting means has a lower coefficient of thermal expansion than the shaft and is tightened to the shaft by a fixing means, which prevents the outer fitting part from expanding and deforming due to temperature changes. This avoids rattling against the shaft.

[Example] Hereinafter, a first example of the present invention will be described in detail with reference to FIGS. 1 to 4.

In FIG. 1, a driving shaft 1 and a driven shaft 2 arranged on the same axis have mutually opposing end surfaces connected by an elastic body. Furthermore, both shafts 1 and 2 are provided with flange portions 3 and 3, respectively.
4 is formed, and the drive shaft l and the driven shaft 2 are connected by a torque sensor 5 fitted onto the flange portion 3.4.

Both the drive shaft 1 and the driven shaft 2 are made of iron, and the stretchable bodies 5a and 5 on the driving side and the driven side of the torque sensor 5 are made of iron.
b is made of a synthetic resin material having a higher coefficient of thermal expansion than iron. Now, the connection structure of both shafts 1 and 2 using the torque sensor 5 will be described below. As shown in FIG. 2, a screw thread is carved in the - portion of the outer peripheral surface of the flange portion 3 of the drive shaft l on the drive side (left side in the figure), and a threaded portion 6 is formed. A smooth fitting portion 7 is formed on the driven side (right side in the figure), and a large diameter separation prevention portion 8 is provided on the driven side of the fitting portion 7 via a step.

In addition, at the end of the drive-side telescopic body 5a serving as the displacement direction converting means forming the drive-side half of the torque sensor 5, the ring-shaped shaft mounting portion 9 has a plurality of diameter-enlarging and Diameter reducing sleeves Sa (Fig. 1) are formed at equal intervals in the circumferential direction. Further, a flange portion 3 is provided on the inner circumferential surface of the shaft mounting portion 9 of the drive side elastic body 5a.
Corresponding to the fitting part 7 and the prevention part 8, a mounting part 1° with a small inner diameter and a retaining prevention part IQa with a larger inner diameter are provided.
Furthermore, a gently tapered surface 11 is formed on the outer circumferential surface of the shaft mounting portion 9 so that the thickness on the drive side is reduced.

The tightening screwed into the threaded part 6 of the flange part 3 is used as a fixing means. A pressing surface 13a corresponding to the tapered surface 11 is formed.

The nut 12 is tightened to the threaded part 6 of the flange part 3, and the pressing surface 13a is pressed against the tapered surface 11, so that the attachment part 10 and the retaining part 10a are fitted into the flange part 3. The torque sensor 5 is pressed by the part 7 and the detachment prevention part 8.
is fixedly held on the drive shaft 1.

As shown in FIG. 3, a thread is formed on the driven side (right side) of the outer peripheral surface of the flange portion 4 of the driven shaft 2.
On the driving side (left side) of the threaded portion 15, a smooth fitting portion 16 having a smaller diameter is formed.

Further, on the inner peripheral surface of the ring-shaped shaft mounting part 17 at the driven side end of the driven side telescopic part 5b of the torque sensor 5, a mounting part 18 corresponding to the fitting part 16 of the flange part 4 is provided. A gentle taper surface 19 is formed on the outer circumferential surface so as to reduce the wall pressure on the drive side. And the shaft mounting part 1
A plurality of diameter expansion/diameter reduction sleeves) Sb (Fig. 1) extending from the driving side end face to the driven side are formed on the shaft 7 at equal intervals in the circumferential direction.

The screwing part 15 of the flange part 4 of the driven shaft 2 is tightened by a pressing piece 21 that protrudes toward the driving side of the nut 20.
The inner circumferential surface of the shaft mounting portion 17 has a shape corresponding to the tapered surface 19 of the shaft mounting portion 17. The nut 20 is tightened and fixed to the threaded portion 15 of the flange portion 4, and the inner circumferential surface of the pressing piece 21 is pressed against the tapered surface 19. The attachment portion 18 is pressed against the fitting portion 16 of the flange portion 4, and the torque sensor 5 is fixedly held on the driven shaft 2.

Furthermore, as shown in FIG. 1, in the driving side telescopic body 5a of the torque sensor 5, the shaft mounting part 9 is connected to a pair of oblique body arms 23 with respect to the bobbin mounting part 22 on the driven side. They are integrally formed so that they can be connected together. Also, in the right telescopic body 5b, the shaft mounting portion 17 is integrally molded so as to be connected to the bobbin mounting portion 24 on the drive side by a pair of diagonal mounting arms 25. . These bobbin mounting parts 22 and 24, that is, the driving side and driven side elastic bodies 5a and 5b are connected via a bobbin 26.

A winding groove 27 is formed in the bobbin 26 so as to extend in the entire circumferential direction, and a capacitor 29 is connected in series to a solenoid coil 28 wound within the winding groove 27. A copper ring 31 is mounted on a support ridge 3o provided at the end of the drive shaft 1 extending from the center of the bobbin 26 toward the driven side within the torque sensor 5. The copper link 31 is always in sliding contact with the inner surface of the bobbin 26 at a position close to the solenoid coil 28.

As shown in FIG. 4, a resonant circuit 32 is composed of a solenoid coil 28, a capacitor 29, and a copper ring 31. When the position of the bobbin 26 changes due to the expansion and contraction of the mounting arms 23, 25 and the solenoid coil 28 is displaced, the inductance of the resonant circuit 32 is increased or decreased.

As shown in FIG. 1, an output coil 34 and an input coil 35 of a detection circuit 33 (to be described later) are placed at a position facing the solenoid coil 28 with a gap therebetween, and in FIG. 4, a pulse current is applied to the output coil 34. By causing the current to flow, the solenoid coil 28 is energized. The inductance of the resonant circuit 32 changes with the relative displacement between the solenoid coil 28 and the copper ring 31. This is the detection circuit 3
3 side, a voltage with a frequency corresponding to the changing inductance is detected by the input coil 35, is taken out as a pulse frequency via an amplifier 36 and a positive feedback circuit 37, and the frequency is converted into a voltage by an f/V converter 38. The drive source is controlled based on the voltage value.

In order to attach the torque sensor 5 to the drive shaft 1 and the driven shaft 2, the diameter of the shaft mounting portion 9.degree. 17 of each telescopic body 5a, 5b is expanded by widening the width of the slit Sa, Sb. Then, the shaft mounting parts 9 and 17 of the expandable bodies 5a and 5b are fitted into the flange parts 3 and 4 of the drive shaft l and the driven shaft 2, respectively, and the slits Sa are formed.

By the action of sb, the shaft mounting parts 9 and 17 are reduced in diameter and fitted onto the flange parts 3 and 4.

After this, tighten the nuts 12 and 20 on each shaft 1. Screw into the flange parts 3 and 4 of 2. Then, tighten the nut 12.
Expandable bodies 5a, 5b on the inner circumferential surface of the pressing pieces 13 and 21 of 20
The tapered surface 11.19 of is tightened and fixed.

Now, in the torque detection device configured as described above, when a rotational force acts on the drive shaft 1 in the direction of the arrow A, the mounting arm 23 of the drive-side telescoping body 5a is bent in one direction, and the driven-side telescoping body 5b is bent in one direction. The mounting arm 25 is bent in the other direction, the bobbin 26 is displaced, the solenoid coil 28 approaches the copper ring 31, and the inductance of the resonance circuit 32 increases. This is detected as a change in frequency by the detection circuit 33, and converted into a voltage signal by the V/f converter 38. Note that the frequency described above increases as the rotation angle of the drive shaft 1 in the direction of arrow A increases.

In addition, both the extensible bodies 5a and 5b of the torque sensor 5 are made of synthetic resin, and the drive shaft 1 and driven shaft 2 are not tightened.
12.20 are each elastic body 5a.

It was made of iron, which has a lower coefficient of thermal expansion than 5b.

Therefore, at high temperatures, the shaft attachment parts 9.17 of the expanding left and right expandable bodies 5a and 5b are thicker than the drive shaft 1 and the driven shaft 2. The surfaces 11 and 19 are only tightened by being pressed against the inner peripheral surfaces of the pressing pieces 13 and 21 of the nuts 12 and 20. Therefore, the coefficient of thermal expansion of the elastic bodies 5a and 5b and both shafts 1 and 2 is reduced. Based on the difference, the expandable bodies 5a and 5b do not wobble on both shafts 1.2.

In addition, when the temperature drops from the above state, the nuts 12 and 20 are used to tighten the shaft mounting portions 9 and 1 of both elastic bodies 5a and 5b.
7 is pressed and held by the drive shaft 1 and the driven shaft 2, respectively, and both elastic bodies 5a.

5b, the inner peripheral surface is the attachment part t of the drive shaft l and driven shaft, respectively.
o, it only presses the outer peripheral surface of 18. The shaft mounting portions 9.17 of the left and right expandable bodies 5a, 5b are fixedly held on the drive shaft 1 and the driven shaft 2. Therefore, the torque sensor 5 will not rattle with respect to the shafts 1 and 2 due to temperature changes.

Next, a second embodiment of the invention will be described with reference to FIG.

In this embodiment, the outer peripheral surface of the shaft mounting portion 17 of the driving side (left side) and driven side (left side) telescopic bodies 5a, 5b (only the driven side is shown) of the torque sensor 5 is tapered so that the driven side plate thickness is small. A tapered surface La is formed by forming a screw thread into a shape, and a tapered surface La is formed on the outer peripheral surface of the shaft mounting portion 17 of the driven side telescopic body 5b. A threaded thread is formed to form a threaded tapered surface Lb.

In addition, on the outer peripheral surface of the shaft mounting part 9 of the drive side telescopic body 5b (not shown), the drive side plate is formed into a tapered shape with a small thickness, and then a screw thread is engraved to form a threaded tapered surface. . After attaching both the telescopic bodies 5a and 5b to the drive shaft 1 and the driven shaft 2, respectively, tighten the
Threaded tapered surfaces La, Lb of shaft mounting parts 9, 17 of a, 5b
It is tightened against.

With this configuration, there is no need to perform thread cutting to form the threaded portions 6, 15 on the flanges 3, 4 of both iron shafts 1, 2, and the shafts 1, 2.

2 is significantly simplified.

Note that the present invention is not limited to the above-described embodiments; for example, (1) the drive shaft 1 and the driven shaft may be made of a material with a low coefficient of thermal expansion other than iron, or the torque sensor 5 may be made of a material with a low coefficient of thermal expansion, or the torque sensor 5 may be made of resin. axis 1,
2. Made of a metal material with a higher coefficient of thermal expansion than 2. ■ Connecting the opposing end surfaces of the driving shaft 1 and driven shaft 2 with a torsion bar. ■ Using one shaft instead of the driving shaft 1 and the driven shaft 2. Any changes, such as attaching the torque sensor 5 to the central portion of the shaft in the longitudinal direction, are possible without departing from the spirit of the invention.

[Effects of the Invention] As described in detail above, the present invention exhibits an excellent effect in that it is possible to accurately control the output from the drive side.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a side view showing the rotational torque detection device together with a drive shaft and a driven shaft, and FIG. 2 is a side view of the rotational torque detection device on the drive shaft side. FIG. 3 is a partially cutaway side view showing how the torque detecting device is installed on the driven shaft side; FIG. 4 is a circuit diagram showing the electrical configuration; FIG. FIG. 5 is a partially cutaway side view showing the conventional example, and FIG. 6 is a side view showing the conventional example. A drive shaft 1, a driven shaft 2, a torque sensor 5 as a displacement direction conversion means, a resonance circuit 32 and a detection circuit 33 as conversion and extraction means, and a shaft mounting part 9 as an external fitting part.
17. Tighten as a fixing means with nuts 12, 20
゜Patent applicant Toyota Automatic Loom Works Co., Ltd. Agent
Patent Attorney On 1) Hironobu (and 1 other person) Drawing 1 Drawing 2

Claims (1)

[Claims] 1. Displacement direction converting means that is fitted onto the shaft that transmits power to the driving side and the driven side and elastically displaces in the axial direction in response to displacement in the rotational direction of the shaft is provided. In a rotational torque detection device formed of a material with a high coefficient of thermal expansion and equipped with a conversion/extraction means for converting the displacement in the axial direction of the displacement direction conversion means into an electric signal and outputting it, the displacement direction conversion means with respect to the shaft is provided. A fixed mounting structure for a rotational torque detection device, in which a tightening and fixing means for tightening and fixing an external fitting portion to a shaft is made of a material having a lower coefficient of thermal expansion than the displacement direction converting means.