JPH0362209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a torque sensor that detects torque transmitted between a pair of rotating shafts arranged on the same line.

[Background of the invention]

In a machine equipped with a rotating shaft, it is important to detect the torque transmitted between the rotating shaft and another rotating shaft connected to the rotating shaft in order to achieve desired control of the machine.

Conventionally, as a torque sensor used to detect such torque, a strain gauge is pasted on the outer surface of the rotating shaft at the connecting portion of both rotating shafts as a signal conversion means for converting the amount of torsional deformation of the rotating shaft into a signal. It is known to use strain gauges to detect torque applied to a rotating body.

However, in the case of a torque sensor using such a strain gauge, since the strain gauge rotates together with the rotating shaft, it is necessary to extract the signal from the strain gauge to the outside via a slip ring, an FM oscillator, or the like. Therefore, for example, if a slip ring is used to extract a signal, the slip ring generates noise and is unreliable, and if an FM oscillator is used to extract a signal, an expensive torque sensor is required. There is a problem.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a torque sensor that is inexpensive, has few failures, and is easy to manufacture, while eliminating the drawbacks of the prior art described above.

[Summary of the invention]

In order to achieve this object, the present invention provides a ring at each end of a first rotating shaft and a second rotating shaft via a plurality of radially extending transmission parts, and a peripheral wall of one ring. By drilling a plurality of through holes in the ring, a diagonal flat plate portion inclined at a predetermined angle is formed at the connecting portion between the ring and each transmission portion, and similarly,
By drilling a plurality of through holes in the peripheral wall of the other ring, a diagonal flat plate portion having the same absolute value of the tilt angle and the opposite inclination direction to the diagonal flat plate portion is provided at the connecting portion between the ring and each transmission portion. The first and second rings are connected so that their axes coincide with each other.
A feature of the present invention is that a non-contact displacement meter detects the amount of displacement of both rings, which are displaced in the thrust direction in response to the torque transmitted between the rotating shafts.

Therefore, first, prior to the embodiments of the present invention, we will explain the basic principles of the torque sensor according to the present invention in the fifth section.
This will be explained with reference to FIGS. 8 to 8.

FIG. 5 is a cross-sectional view of the detection section, and FIG. 6 is a side view of the detection section. In these figures, 1 indicates the rotation axis;
2 is a ring connected to the rotating shaft 1 via three oblique flat plates 3. Each oblique plate 3 is inclined at the same angle θ with respect to the axis of the rotating shaft 1, and both ends of each are firmly fixed to the outer circumferential surface of the rotating shaft 1 and the inner circumferential surface of the ring 2. ing.

In the detection unit configured in this way, assuming that torque M ₀ is transmitted between the rotating shaft 1 and the ring 2, the radius of the rotating shaft 1 is r, the number of oblique flat plates 3 is n, and the oblique flat plate If the length, width, and thickness of 3 are l, b, and t, respectively, a force Mo/nr acts on the oblique plate 3 of 1 in a direction perpendicular to the axis of the rotating shaft 1, and this force Mo/ Each oblique plate 3 is deflected in the direction of the thin wall of the plate due to nr.

7 and 8 are for explaining the relationship between the force acting on the diagonal flat plate 3 and the amount of deflection at this time, and FIG. 8 shows the diagonal flat plate 3 shown in FIG. This is a conceptual diagram.

Now, as shown in Fig. 8, we assume a completely fixed to vertical sliding fulcrum beam with one end completely fixed and the other end sliding while being regulated by a vertical wall, and this beam is likened to a diagonal flat plate 3. Considering the case where a downward force W acts on the sliding part of the beam, the moment M at any distance x from the sliding part is M=-Wx+M ₁ (1). (However, M ₁ is the unknown moment at x = 0) If the deflection of the beam from the unloaded state is V, the elastic modulus of the beam is E, and the cross-sectional moment of inertia of the beam is I, then the beam at any point x is _The curvature d ^{2 v} / ^{dx 2} of /dx is obtained as follows: dv/dx=1/EI(W/2x ² −M ₁ x+C ₁ ) (3) (C ₁ is a constant).

Since the deflection angle is 0 both at the point x = 0 and at the fixed end of the beam (i.e. x = l), C ₁ = 0 can be found by substituting x = 0 into equation (3), and similarly,
By substituting x=l into equation (3), M ₁ =Wl/2 is obtained.

Substituting these into (3), dv/dx=1/EI(W/2x ² -W/2x)=W/2EI(x ²
−lx)(4), and by integrating this equation (4) to find the deflection v, we get v=W/2EI(x ³ /3−l/2x ₂ +C ₂ ) …(5) (however, C ₂ is a constant).

Since the beam is completely fixed at the right end, in equation (5), v at x=l is 0, and _C2 = ^-l3 /3+ ^l3 /2= ^l3 /6...(6) is obtained. Therefore, by substituting this into equation (5), v=W/2EI(x ³ /3-l/2x ² +l ₃ /6)...(7) is obtained.

Substituting x=0 into this equation (7) to find the amount of deflection v ₁ of the sliding end of the beam, v ₁ = Wl ³ /12EI (8). Here, since W is the component of the force M ₀ /nr acting on the oblique plate 3 in the direction perpendicular to the oblique plate 3, W=
M ₀ /nrcosθ, and since the cross-sectional shape of the oblique plate 3 is rectangular, I=bt ³ /12, and by substituting these into equation (8), v ₁ = M ₀ cosθ・l ³・12/nr・12E・bt ³ =M ₀ l ³ cosθ/Enrb
t ³ …(9).

Since the ring 2 is considered to be fixed to the sliding end of the beam (that is, the oblique plate 3), if the displacement amount of the ring 2 in the thrust direction is δ, then (9)
According to the ^formula , δ= _v1・sinθ= _M0l3cosθ / ^Enrbt3sinθ = ^Mol3sin2θ / ^2Enrbt3 ...(10). In this equation (10), b, t, l, r,
Since both E and n are known, by measuring the displacement δ of the ring 2 in the thrust direction, the torque M ₀ transmitted between the rotating shaft 1 and the ring 2 can be determined.
can be measured.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a schematic diagram showing an embodiment of a torque sensor according to the present invention. In this figure, 4 is a main body, and a first rotating shaft 7 and a second rotating shaft 8 are rotatably supported on the main body 4 via bearings 5 and 6, respectively. The axes of both rotating shafts 7 and 8 are on the same line, and both rotating shafts 7 and 8 are regulated so as not to be displaced in the thrust direction.

FIG. 2 is a side view showing details of the first rotating shaft 7, and FIG. 3 is a sectional view taken along the line B-B in FIG. 2. As shown in these figures, the first rotating shaft 7 is At the left end, there is a rectangular column-shaped transmission part 9a and a thin flat plate-shaped first transmission part 9a.
A first ring 9 is connected to the first ring 9 via the oblique flat plate portion 9b. Three transmission parts 9a extend radially from the outer peripheral surface of the first rotating shaft 7, and the first oblique flat plate part 9b connects the tip of each transmission part 9a and the first ring 9.
There are six plates in total, two facing each other so as to communicate with each other. It is sloping.

The first rotating shaft 7 equipped with the first ring 9 having such a structure does not use coupling means such as welding or bolts,
It can be made in one piece from metal materials. An example of the processing method will be described below.

First, a solid metal material is cut using a lathe,
As shown in FIG. 4, a first rotating shaft 7 with predetermined dimensions
and a first ring 9 having a wall thickness of B. Next, the connecting portion between the first rotating shaft 7 and the first ring 9 is processed by electric discharge machining, wire cutting, laser machining, drilling, etc.
Drill eyebrow-shaped holes 10 (see Figure 3), each hole 1
Processing is performed so that the first rotating shaft 7 and the first ring 9 are connected to each other in the portion left between the two.
Finally, new through holes 11 are made at three locations on the circumferential wall of the first ring 9 by electrical discharge machining, drilling, etc., facing toward the hole 10 from the outside. These through holes 11
A total of 6 holes are drilled, 2 at each location, leaving a predetermined wall thickness T, and this creates a rectangular prism-shaped transmission section 9a with length, width, and thickness dimensions of L, B, and T, respectively. A certain first oblique flat plate portion 9b is formed (see FIGS. 3 and 4).

Returning to FIG. 1, a second ring 12 is connected to the right end of the second rotating shaft 8 via a rectangular prism-shaped transmission part 12a and a thin flat plate-shaped second oblique flat plate part 12b.
are installed in succession. Three transmission parts 12a extend radially from the outer circumferential surface of the second rotating shaft 8, and the second oblique flat plate part 12b is configured to communicate between the tip of each transmission part 12a and the second ring 12. There are six plates in total, two facing each other, and each plate has the same absolute value of the inclination angle as the first oblique flat plate part 9b, and the inclination direction is opposite, that is, an angle of -θ with respect to the axis. It is also sloped. These second rotating shaft 8, transmission section 12a, second oblique flat plate section 12b, second
The ring 12 is also made integrally from a metal material by the same processing method as that for the first rotating shaft 7 side described above, and the first ring 9 and the second ring 12 are made by using the unevenness of the opposing surfaces. They are fixed by welding 13 or the like in a precisely fitted state.

Reference numeral 14 denotes a non-contact type displacement meter such as a magnetic type or an optical type, and the displacement meter 14 has a detection part 14a as a first
The ring 9 is mounted inside the main body 4 so as to face the end face of the ring 9 . The displacement meter 14 detects minute displacements of the integrated rings 9 and 12 in the thrust direction, and input/output operations to the displacement meter 14 are performed from outside the main body 4 via a cord 15.

In the torque sensor configured in this way,
Now, the first rotating shaft 7 is rotationally driven by a rotating machine (for example, a motor) not shown, and the first rotating shaft 7
Assuming that torque M ₀ is transmitted between the first rotation shaft 7 and the second rotating shaft 8, the torque M ₀ is Ring 9 → second ring 12 → second oblique flat plate portion 12
b→transmission part 12a→transmitted to second rotating shaft 8. Here, the number of each of the transmission parts 9a, 12a is N (N=3 in the embodiment), and the distance from the axis of the rotating shafts 7, 8 to the radial center of the oblique plate parts 9b, 12b is R( (see FIG. 3), a force M ₀ /2NR acts on one oblique flat plate portion 9b, 12b, and each oblique flat plate portion 9b, 12b is deflected by this force M ₀ /2NR. At this time, the first ring 9 is displaced in the thrust direction due to the deflection of the first oblique flat plate portion 9b, and the second ring 12 is displaced due to the deflection of the second oblique flat plate portion 12b.
The thrust direction displacement of both oblique flat plate portions 9b, 12
Since b are opposite to each other at the same angle, they are in the same direction and in the same amount.

Therefore, when torque M ₀ is transmitted between both rotating shafts 7 and 8, both rings 9 and 12 are as follows: δ=L ³ sin2θ/4ENRBT ³・M ₀ where E: Elasticity of oblique flat plate portions 9b and 12b Coefficient N: Number of each of the transmission parts 9a, 12a R: Distance from the axis to the radial center of the slanted flat plate parts 9b, 12b B: Width of the slanted flat plate parts 9b, 12b T: Number of the slanted flat plate parts 9b, 12b Thickness L: Length of the oblique flat plate portions 9b, 12b θ: Displacement in the thrust direction by the angle formed by the axis and the oblique flat plate portions 9b, 12b, and measure the amount of displacement δ with the displacement meter 14. Torque M ₀ can be detected by

In this embodiment, both rings 9 and 12 are only displaced in the thrust direction, and both rotation shafts 7 and 8
is not displaced in the thrust direction, for example, even if a gear is connected to the second rotating shaft 8 and another gear is meshed with the gear, no force in the thrust direction will act on the tooth surfaces of both gears. , therefore, the rotation axes 7, 8
This is particularly effective when a rotating body is connected to which a frictional force in the thrust direction is applied.

Further, since the mechanism related to torque detection, that is, the rings 9 and 12 and the displacement meter 14 that detects the displacement of the rings 9 and 12 in the thrust direction, is arranged inside the main body 4, a torque sensor with fewer failures can be provided.

Furthermore, the first rotating shaft 7-side structure having the first ring 9 and the second rotating shaft 8-side structure having the second ring 12 are each made of a metal material by cutting, drilling, etc. Since it can be produced in one piece, it is possible to improve the machining accuracy and to achieve concentricity of both rotating shafts 7 and 8 with high precision.

In the above embodiment, the pair of oblique flat plate portions 9a,
Although the explanation has been made using three transmission parts 9a and 12a each having three transmission parts 9a and 12b connected in series, the transmission part 9
The number of a and 12a is not limited to this, and it is sufficient if each number is two or more.

Further, in the above embodiment, the motor is used as an example of the rotating body connected to the first rotating shaft 7, but other rotating bodies may be connected to the first rotating shaft 7, and similarly, the motor may be connected to the first rotating shaft 7. A rotating body such as a gear, a pulley, or a chain gear can also be connected to the second rotating shaft 8.

Further, in the above embodiment, the displacement gauge 14 is arranged opposite to the end face side of the first ring 9, but the displacement gauge 14 is arranged opposite to the end face side of the second ring 12, The displacement of the ring 12 in the thrust direction may also be detected.

〔Effect of the invention〕

As explained above, according to the present invention, the torque transmitted between two rotating shafts arranged on the same axis can be detected as the displacement in the thrust direction of the ring using a non-contact displacement meter, which is inexpensive. A torque sensor with fewer failures can be provided, and since both rotating shaft side structures each having a ring can be processed from a single piece, a torque sensor that is easy to manufacture can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a torque sensor according to the present invention, FIG. 2 is a side view of the rotating shaft with a ring shown in FIG. 1, and FIG.
4 is a sectional view of the structure in the middle of machining the rotating shaft with a ring shown in FIG. 2, and FIGS. 5 to 8 are explanatory views showing the basic principle of the torque sensor according to the present invention. FIG. 5 is a cross-sectional view of the detection section, FIG. 6 is a side view of the detection section, FIG. 7 is an explanatory diagram showing the relationship between force and displacement acting on the oblique flat plate, and FIG. 8 is a diagram showing the relationship between the force and displacement of the oblique flat plate. It is a conceptual diagram explaining a deflection state. 4... Main body, 5, 6... Bearing, 7... First rotating shaft, 8... Second rotating shaft, 9... First ring, 9a... Transmission part, 9b... First Oblique flat plate part,
DESCRIPTION OF SYMBOLS 10... Hole, 11... Through hole, 12... Second ring, 12a... Transmission part, 12b... Second oblique flat plate part, 14... Displacement meter, 14a... Detection part, 15...
…code.

Claims (1)

[Claims] 1 A first rotating shaft and a second rotating shaft are rotatably supported in the main body so that their axes coincide with each other, and transmission is transmitted between the first rotating shaft and the second rotating shaft. In a torque sensor that detects torque, a first ring is provided at an end of the first rotating shaft via a plurality of transmission parts extending radially, and a connection part between these transmission parts and the first ring, A through hole is formed leaving the first oblique flat plate part inclined at a predetermined angle with respect to the axis, and the second rotating shaft is connected to the end of the second rotating shaft via a plurality of transmission parts extending radially. A ring is provided, and a connection portion between the transmission portion and the second ring is provided with a
A through hole is bored, leaving a second oblique flat plate portion whose inclination angle is equal in absolute value to that of the first oblique flat plate portion and whose inclination direction is opposite, and a through hole is bored between the first ring and the second ring. The first and second rings are connected such that their axes coincide with each other, and a non-contact displacement meter capable of detecting the displacement of the ring in the thrust direction is disposed on the end face of one of the first and second rings. A torque sensor characterized by the fact that it is installed.