Torque sensor with a rotary differential transformer containing a spring body

Abstract

To detect angle information and torque using no conventional torsion bar.SOLUTION: A torque sensor having a rotary type differential transformer having a built-in spring body includes: a main shaft 1 rotatably provided in a housing 2; a spring body 8A composed of a torsion spring 8 provided in the housing 2 and positioned at an outer periphery 1B of the main shaft 1; and a rotary type differential transformer 5 provided at an end section 4 of the main shaft 1. A first spring hook 10 and a second spring hook 11 located at a first end section and a second end section of the spring body 8A are structured to be able to receive tension in a reverse direction of each other and detect a rotation angle of the main shaft 1 and a torsion angle of the spring body 8A as angle information.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a torque sensor having a rotary differential transformer with a built-in spring body. In particular, when the main spindle rotates more than a certain degree, one of the spring hooks contacts a stopper inside the housing, preventing excessive rotation, and it relates to a novel improvement that enables a function as a torque sensor that combines the principle of a well-known RVDT (rotary differential transformer) and a torsion spring mechanism.

Background Art

[0002] Conventionally, as this type of torque sensor that has been used, as shown in FIGS. 2 and 3 of Patent Document 1 (not shown), a steering torque sensor for detecting steering torque during vehicle steering has been disclosed. This steering torque sensor includes a torsion bar provided in the middle part of a steering shaft, a moving core guided to be displaceable only in the axial direction on one end side of the torsion bar, a transmission mechanism for converting the torsional displacement of the other end side with respect to one end side of the torsion bar into the axial displacement of the moving core, and a differential transformer coil held on the vehicle body side so as to be in sliding contact with the moving core via an insulating material to output an electrical signal corresponding to the displacement of the moving core. The moving core contains at least one of chromium and aluminum and 0.3 wt% or less of carbon, and the sliding contact surface of the moving core with the insulating material is subjected to soft nitriding treatment. When steering torque is generated in the steering shaft, the torsion bar twists, and a pin provided on a sleeve moves relatively in the circumferential direction with respect to the sleeve. Therefore, these pin and the spiral elongated hole engaged with the pin are used as a transmission mechanism to convert the torsional displacement of the torsion bar into the axial displacement of the moving core.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] Conventional torque sensors, for example, were configured as described above. As such, when optical components, electronic components, and machined parts—which are not commonly used in today's environment—were used in applications such as electric steering systems in automobiles, durability issues arose in harsh environments.

[0005] The present invention was made to solve the above-mentioned problems, and in particular, when the main shaft rotates beyond a certain point, one of the spring hooks contacts a stopper inside the housing, thereby preventing excessive rotation, and provides a torque sensor having a rotary differential transformer that incorporates a spring body combining a well-known RVDT and a torsion spring mechanism. [Means for solving the problem]

[0006] The torque sensor having a rotary differential transformer with a built-in spring body according to the present invention comprises a main shaft rotatably mounted in a housing, and a spring body consisting of a torsion spring located inside the housing and on the outer circumference of the main shaft, A rotary differential transformer provided at the end of the main shaft, a first spring hook and a second spring hook provided on the outer circumference of the main shaft and formed separately from each other, and an arm provided on the main shaft that pushes the first spring hook or the second spring hook, The structure comprises a rotary differential transformer provided at the end of the main shaft, wherein the first and second spring hooks located at the first and second ends of the spring body are designed to be subjected to tension in opposite directions, and the rotational speed of the rotation angle of the main shaft and the torsional angle of the spring body are detected as angular information, and the spring body is made of a spring, and the first and second spring hooks are designed to bend the ends of the spring into a U-shape. attitude The structure is such that a stopper is provided inside the housing to prevent excessive rotation of the main shaft. [Effects of the Invention]

[0007] The torque sensor having a rotary differential transformer with a built-in spring body according to the present invention has the above configuration and therefore can obtain the following effects. In other words, because torsion bars are not used, manufacturing becomes easier. Furthermore, angle information can be obtained by using a general-purpose measuring instrument to measure the voltage output from a rotary differential transformer. Furthermore, rotary differential transformers can also detect open circuits by monitoring the sum voltage calculated from the output voltages of the two phases, thus enabling fault detection. Furthermore, by installing a torsion spring inside the housing, the stopper strength is improved, allowing the use of springs with greater torsional torque, and thus improving the torque detection range. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing a torque sensor having a rotary differential transformer with a built-in spring body according to an embodiment of the present invention. [Figure 2] This is an enlarged plan view showing the spring hook in Figure 1. [Figure 3] This is a plan view of the initial position (0°) of the principal axis in Figure 3. [Figure 4] This is a plan view of the principal axis of Figure 3 rotated by 100°. [Figure 5] Figure 3 is a plan view showing the state in which the main shaft is rotated 125° and is in contact with the stopper, causing it to stop. [Figure 6] This is a plan view showing the positional changes of the spring hook due to spindle rotation, etc. [Figure 7] This is a cross-sectional view AA in Figure 6. [Figure 8] This is a cross-sectional view of BB in Figure 6. [Figure 9] Figure 6 is a cross-sectional view of CC. [Figure 10] This is a plan view showing a pair of spring hooks in both a rotating and stationary position. [Figure 11] This is a characteristic diagram showing the output of the RVDT used in an embodiment of the present invention. [Figure 12] This is an output diagram of a torsion spring used in an embodiment of the present invention. [Figure 13]Perspective view of the torsion spring in the embodiment of the present invention. [Figure 14] Output diagram showing the torque of the RVDT in the embodiment of the present invention.

Embodiment for Carrying Out the Invention

[0009] In the present invention, when the main shaft rotates more than a certain amount, one spring hook contacts the stopper inside the housing, preventing excessive rotation, and a torque sensor is obtained which incorporates a spring body combining a well-known RVDT and a torsion spring mechanism.

Example

[0010] Hereinafter, a preferred embodiment of a torque sensor having a rotary differential transformer incorporating a spring body according to the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a main shaft rotatable in both the clockwise (CW) and counterclockwise (CCW) directions. This main shaft 1 is rotatably provided in a housing 2 via a bearing 2A. Outside the housing 2 and at the end 4 of the main shaft 1, a rotary shaft 6 of a well-known RVDT (well-known rotary differential transformer) 5 attached to the housing 2 is connected to the main shaft 1. Between a pair of first and second spring hooks 10 and 11 provided on the outer periphery of the main shaft 1 and formed separately from each other, a spring body 8A composed of a torsion spring 8 is sandwiched.

[0011] As shown in FIG. 2, arms 11A provided on each of the spring hooks 10 and 11 are attached to the main shaft 1, and as the main shaft 1 rotates, the arms 11A push the spring hooks 10 and 11 one after another, and as a result, the torsion spring 8 is twisted. The first spring hook 10 in the direction opposite to the rotation direction of the main shaft 1 is in contact with either the first or second stopper 13 or 14, and the spring hook 10 is held in a stationary state without rotating.

[0012] As shown in FIGS. 3 to 5, it is provided on the main shaft 1. When viewed from the shaft end of the main shaft 1 in the CCW rotation direction with respect to the housing 2, in FIG. 3, when the main shaft 1 is in the initial position (0°), that is, the main shaft 1 shows a stopped state. FIG. 4 shows the state where the main shaft 1 has rotated 100° from the state of FIG. 3, and the first spring hook 10 also rotates simultaneously and is twisted, generating a predetermined torque. In FIG. 5, when the main shaft 1 rotates more than a certain amount, the first spring hook 10 rides on the second stopper 14 among the first and second stoppers 13, 14 in the housing 2 (a state of 125° rotation). If the spring hook 10 of the main shaft 1 is pushed by the stopper 14 further, the spring hook 10 may be damaged. Therefore, it protects the spring of the first spring hook 10. <000​​​​​​​​​​​​​​​​The first and second spring hooks 10 and 11 located at the first and second ends of the spring body 8A are designed to be subjected to pulling in opposite directions, and this can be detected as information on the rotation angle of the main shaft 1 and the torsional angle of the spring body 8A. The spring body 8A is made of a well-known spring, and as shown in Figure 13, the first and second spring hooks 10 and 11 have their respective ends bent into a U-shape (so that the U-shaped parts 8M and 8N). Furthermore, the first and second stoppers 13 and 14 within the housing 2 are structured to prevent excessive rotation of the main spindle 1 in the CW and CCW directions.

[0016] Furthermore, since the aforementioned RVDT5 is a well-known device, Figure 11 shows the output voltage details and Figure 12 shows the output (torque) state of the torsion spring 8.

[0017] The torque outputs of the torsion spring 8 in Figure 13 and the RVDT5 in Figure 14 are as follows: The output of the RVDT changes proportionally to the angle θ, with respect to the inclination (sensitivity) k1. The spring constant of a torsion spring is uniquely determined by its material, number of turns, etc. To briefly explain the measurement method, 1. Measure the angle θ1 from the output voltage of the RVDT. E = k1 × θ1 2. Convert the torque from the spring constant k2 and θ1. T = k2 × θ1 The output Va-Vb of the RVDT becomes a negative voltage when it rotates in the negative direction. This allows us to confirm the direction of rotation (see the case of θ2 in Figure 14). Torque can be converted as an absolute value (because it depends only on the twist angle from the starting point, and not on the direction of rotation). [Industrial applicability]

[0018] The torque sensor having a rotary transformer with a built-in spring body according to the present invention has the spring body mounted on the main shaft, detects the torsional angle information generated in the spring body when the main shaft rotates left and right as torque, and ensures the safety of each spring hook with each stopper. [Explanation of Symbols]

[0019] 1 spindle 1A Torque Sensor 1B outer circumference 2 Housing 2A bearing 4 ends 5. RVDT (Rotating Differential Transformer) 6 rotation axes 8 Torsion spring 8A Spring Body 8M, 8N U-shaped part 10. First spring hook 11. Second spring hook 11A arm 13 First Stopper 14. Second Stopper

Claims

1. The device comprises a main shaft (1) rotatably mounted in a housing (2), a spring body (8A) consisting of a torsion spring (8) located inside the housing (2) and on the outer circumference (1B) of the main shaft (1), a rotary differential transformer (5) provided at the end (4) of the main shaft (1), a first spring hook (10) and a second spring hook (11) provided on the outer circumference of the main shaft (1) and formed separately from each other, and an arm (11A) provided on the main shaft (1) that pushes the first spring hook (10) or the second spring hook (11), A torque sensor having a rotary differential transformer incorporating a spring body, characterized in that the first spring hook (10) and the second spring hook (11) located at the first and second ends of the spring body (8A) are capable of being subjected to tension in opposite directions, and the rotation angle of the main shaft (1) and the torsion angle of the spring body (8A) are detected as angular information.

2. A torque sensor having a rotary differential transformer incorporating the spring body (8A) according to claim 1, characterized in that the spring body (8A) is made of a spring, and the first and second spring hooks (10, 11) have the ends of the spring bent into a U shape.

3. A torque sensor having a rotary differential transformer with a built-in spring body according to claim 1 or 2, characterized in that stoppers (13, 14) are provided inside the housing (2) to prevent excessive rotation of the main shaft (1).

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