JPH043242Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a torque detection device in an electric power steering device.

(Prior Art) Generally, an electric power steering device connects a first shaft to which a steering wheel is attached and a second shaft connected to a steering wheel via a link such that a predetermined relative angular displacement is possible. and the first torque generated in response to the torque applied between the two shafts.
The relative rotation angle between the shaft and the second shaft is electrically detected, and the second shaft is rotationally driven by a servo motor or the like based on the detection signal.

Conventionally, in this type of device, it is common to apply torque to an elastic member and measure the amount of deformation of the member. A helical spring (or helical coupling) 105 is interposed between the first shaft 1 and the first shaft 1 to enable a predetermined relative angular displacement.
A recess 107 having a rectangular shape as shown in the drawing is provided at the end of the second shaft 108, and a roughly rectangular cross section is provided at the end of the second shaft 108 to be rotatably fitted in the recess 107 of the first shaft 106. A convex portion 109 of the shape is formed, and a concave portion 1
An elastic member, such as a rubber member 111, is housed in each corner 110 of 07 and connected to enable a predetermined relative angular displacement. Also, Figures 11 and 12
The one shown in the figure has a second shaft 11 at the end of the first shaft 112.
The recess 1 that fits into the convex portion 115 formed at the end of the recess 1
14 is formed, and grooves 116 and 117 that align with each other are formed along the diameter direction at the same end, and plate springs 118 and 118 having the cross-sectional shape shown in the figure are interposed in the grooves 116 and 117. The relative angular displacements of are possible.

(Problems to be Solved) However, in each of the above devices, when a helical spring is installed, the helical spring 1
Since torque is repeatedly applied to the 05 in the twisting direction and the unwinding direction, it has poor durability.
Further, since the balance point when the input torque is 0 is determined only when the helical spring is in its natural state, adjustment after assembly is required. In addition, since the rubber member 111 is itself an elastic body, it is difficult to adjust the balance point when the input torque is 0 after assembly, and restoration due to hysteresis, temperature, etc. There are problems such as lack of sex. Further, in the case where the leaf spring 118 is used as the elastic member, there are problems such as not being able to obtain linearity in the load-strain diagram.

(Means for Solving the Problems) The present invention was made to solve the above-mentioned conventional problems, and it is possible to provide exactly the same characteristics for left and right rotations, and to accurately detect angular displacement by torque. The purpose of the present invention is to provide a torque detection device for an electric power steering device that can be used in an electric power steering device. A first ring body is provided, and the other shaft is provided with a second ring body having a ring groove into which the first link body is fitted. A torque detection device for an electric power steering device is provided with one or more spring grooves that align with each other and are open on the outer circumferential side to horizontally hold a helical spring.

(First Embodiment) Next, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 5 shows the entire electric power steering device for a battery-type reach forklift. In the figure, 1 is the first shaft to which the steering wheel 2 is fixed, and 3 is connected to the first shaft 1 via a torque detection device 4. The second axis is
The second shaft 3 is connected to a drive unit 8 via a chain transmission mechanism 5, a transmission shaft 6, and a gear train 7. Note that the steering drive wheels 9 in the drive unit 8 are rotationally driven by a drive motor 10 via a gear transmission (not shown) in a gearbox 11. Reference numeral 12 denotes a servo motor for steering, which rotates the second shaft via a reduction gear mechanism 13 according to instructions from a controller 14 .

Next, the torque detection device 4 is formed as follows. That is, a flange 15 of a predetermined diameter is integrally formed on the first shaft 1, and a first ring body 16 of a predetermined diameter is integrally formed on the lower surface of the flange 15 as shown in the figure, centered on the axis. Further, a stepped shaft portion 17 is integrally formed in the lower part of the flange 15, and a connecting hole 18 having a predetermined diameter d1 is formed through the lower end of the coaxial portion 17. Further, a flange 19 corresponding to the flange 15 of the first shaft 1 is integrally formed at the upper end of the second shaft 3 in the drawing, and a first ring body 16 formed on the first shaft 1 is formed on the upper surface side of the flange 19. A second ring body 20 having a ring groove 21 that is rotatably fitted concentrically is integrally formed.
At the axis of the shaft 3, there is a stepped shaft portion 1 formed on the first shaft 1.
An insertion hole 22 into which the shaft portion 7 is rotatably inserted is bored, and a hole 23 is formed through the second shaft 3 so that the shaft portion 17 is aligned with the connecting hole 18 when the shaft portion 17 is inserted. Further, in a state in which the first ring body 16 and the second ring body 20 are rotatably fitted, a spring of a predetermined width is provided in the diametrical direction of both the ring bodies 16 and 20 to elastically hold the helical spring 26. Grooves 24 and 25 for springs are formed so that they can be aligned, respectively.
25 is open to the outside (outer circumferential side). Also,
The helical spring 26 is fitted into the spring grooves 24 and 25, and is inserted into the spring grooves 24 and 25 from the outer opening thereof with their axes horizontal, and is held in place by extremely small mounting spring pressure. End faces 16 of grooves 24 and 25
a, 20a and end surfaces 16b, 20b are aligned at the same level to set a neutral position. The first shaft 1 and the second shaft 3 are connected by a connecting pin 27, and the diameter d2 of the connecting pin 27 is smaller than the diameter ad1 of the connecting hole 18 by Δd. 1 is loosely connected to the connecting pin 27, and the first shaft 1 is allowed to undergo relative angular displacement with respect to the second shaft 3 within the range of the difference in diameter. Further, although not shown as a detection means, a magnet is attached to each of the first shaft 1 and the second shaft 3, and a Hall element is provided on the machine base side to detect the relative angular displacement of both shafts 1 and 3. The detection signal is input to the controller 14.

Note that 28 is attached to the second shaft 3 and constitutes the reduction gear mechanism 13 with gears.

Next, the operation of the first embodiment configured as described above will be explained.

When the first shaft 1 is rotated, for example, to the left by the steering wheel 2, the first shaft 1 is
The ring body 16 is guided by the second ring body 20, and the helical spring 26 that has landed in the spring grooves 24 and 25 is received by the end surface 20b of the second ring body 20, and is also held by the end surface 16a of the first ring body 16. It is compressed and the first axis 1 is subjected to a relative angular displacement. This relative angular displacement is detected by a detection means, and a detection signal of the displacement amount and direction is input to the controller 14. Therefore, the servo motor 12 is driven in response to the torque added according to the instruction from the controller 14, and the second torque is transmitted through the reduction gear mechanism 13.
Axis 3 is rotated. As a result, the drive unit 8, that is, the steering drive wheel 9, is steered to the left via the chain transmission mechanism 5, the transmission shaft 6, and the gear train 7. At this time, based on the rotation of the second shaft 3, the compressed state of the helical spring 26 is returned to the expanding direction.
When the rotational operation of the steering wheel 2 continues one after another in the direction of rotation, the above operations are performed continuously. And steering wheel 2
When the operating force is released, further steering of the steering drive wheels 9 is stopped. Further, when the steering wheel 2 is rotated to the right, the helical spring 26 is rotated on the end surface 20a of the second ring body 20, contrary to the above description.
At the same time, it is compressed in the opposite direction by the end surface 16b of the first ring body 16, and the steering drive wheel 9 is steered to the right.

Therefore, since this embodiment is configured as described above, the first shaft 1 is provided with the concentric first ring body 16, and the second shaft 3 is provided with the first ring member 16.
A second ring groove 20 that rotatably fits into the second
The ring body 20 is formed concentrically, and both ring bodies 16,
By rotatably fitting the rings 20 together, the axes of the rings 16 and 20 can be easily aligned and assembled.
It can be assembled extremely easily by inserting the spring grooves 24 and 25 into the matching outer openings with their axes horizontal, and the end surfaces 16a and 20a of the grooves 24 and 25 can be easily assembled using the same helical spring 26. Since the end faces 16b and 20b are maintained aligned and the neutral point can be easily set, there is no need to adjust the neutral point after assembly as in the conventional case.
Since the shaft is expanded and contracted along its axis without any force, no hysteresis occurs. Therefore, it is possible to provide exactly the same characteristics for left and right rotations, and angular displacement can be accurately detected by torque.
Note that even if the spring constants of the left and right helical springs 26 are different, the characteristics will not become nonlinear because the sum of both spring forces acts in both left and right rotations.

Further, both ring bodies 16 and 20 and the spring groove 2 constituting the detection device 4 for the first shaft 1 and the second shaft 3 are also included.
4 and 25 have extremely simple shapes, so they are easy to work with, and the number of parts is small, so parts management and maintenance can be easily performed.

(Second Embodiment) Next, the second embodiment of the present invention is shown in FIGS. 6 and 7.
To explain according to the figure, in this second embodiment, four helical springs 26 are attached to the first shaft 1.
A cylindrical convex portion 29 having the same height as the first ring body 16 is formed at the center of the flange 15 in place of the stepped shaft portion 17 of the first embodiment, and the convex portion 29 has a predetermined diameter d1 in the diametrical direction. A connecting hole 30 is provided therethrough. Further, a convex portion 31 that rotatably fits into the cylindrical convex portion is formed at the center of the flange 19 of the second shaft 3, and the convex portion 31 has a diameter d that matches the connecting hole 30 in the diametrical direction
One hole 32 is provided therethrough. Also, both shafts 1 and 3
In the first ring body 16 and second ring body 20 formed in the figure, spring grooves 24 and 25 similar to those in the first embodiment are formed at positions separated by 90° as shown in the figure. Both shafts 1 and 3 formed in this manner are connected by a connecting pin 33, square spring grooves 24 and 25 are aligned, and a helical spring 26 is fixed in the same way as in the first embodiment. Note that the connecting pin 33 is connected to the second
It is tightly fitted into the hole 32 of the shaft 3, and the diameter d2 of both ends thereof is
is formed to have a smaller diameter by Δd than the diameter d1 of the connecting hole 30, and the first shaft 1 is connected to the connecting pin 33 in a loose fit manner, and the first shaft 1 has a diameter within the range of the difference in diameter with respect to the second shaft 3. relative angular displacement is allowed. Therefore, this second embodiment can also operate in the same manner as the first embodiment.

In each of the above-mentioned embodiments, cases where two and four helical springs 26 are used are illustrated, but the invention is not limited to this, and a structure in which one or three helical springs 26 are landed may be used. In addition, the first ring body 1
6 is provided on the first shaft 1 and the first ring body 20 is provided on the second shaft 3, but the configuration may be reversed.

(Effect of the invention) As described above, according to the invention, the first shaft has a concentric first ring body, and the second shaft has a ring groove in which the first ring body is rotatably fitted. having second
By forming the ring bodies concentrically and rotatably fitting both ring bodies, it is possible to easily align their axes and assemble them, and in this fitted state, the helical spring is It is extremely easy to assemble by inserting the shaft center horizontally through the outer opening of the matching spring groove, and the end faces of the groove are maintained aligned by the same helical spring, making it easy to set the neutral point. can be set, there is no need to adjust the neutral point after assembly as in the past, and the helical spring can be expanded and contracted along its axis without any force, so systeresis does not occur.
It is possible to provide exactly the same characteristics for left and right rotations, and angular displacement can be accurately detected by torque. In addition, the ring bodies and spring grooves that make up the detection devices for the first and second axes have extremely simple shapes, making them easy to work with, and the small number of parts makes parts management and maintenance easy. be able to.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a partially cutaway front view of the torque detection section, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 1 is a cross-sectional view taken along the line 1, FIG. 4 is an explanatory diagram of the function of the ring body, FIG. 5 is an explanatory diagram showing an electric power steering device for a battery type reach forklift, and FIGS. 6 and 7 are diagrams of the present invention. Showing a second example,
Fig. 6 is a partially cutaway front view of the torque detection section, Fig. 7 is a sectional view taken along the - line in Fig. 6, and Figs.
The figure is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1...First shaft, 3...Second shaft, 4...Torque detection device, 16...First ring body, 20...Second ring body, 24, 25...Spring groove, 26...Trail Winding spring, 27, 33...connecting pin.

Claims (1)

[Scope of utility model registration request] A first shaft is provided so as to be movable relative to the second shaft via a pin, a first ring body is provided on one of the two shafts, and the first link body is fitted on the other shaft. A second ring body having a ring groove is provided, and when both ring bodies are rotatably fitted, the two ring bodies are aligned with each other and open on the outer circumferential side, so that the helical spring can be horizontally hit. A torque detection device for an electric power steering device, which is provided with one or more retaining spring grooves.