JP4722271B2 - Torque detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a torque detection device, and more particularly to a torque detection device suitable for detection of driving torque of a bicycle that has wheels and can travel, and a bicycle that cannot travel, such as a training exercise bike.
[0002]
[Prior art]
In recent years, the use of bicycles for health maintenance and dieting has increased, but it is extremely useful to know the energy that you have consumed in exercising. For this purpose, for example, Japanese Patent Laid-Open No. Hei 2-19735 has been disclosed in which a driving torque necessary for traveling a bicycle is detected by a torque detection device and energy consumption (momentum) can be calculated based on the output of the torque detection device. No. 8 or Japanese Patent Laid-Open No. 8-338774.
[0003]
[Problems to be solved by the invention]
However, the above-described conventional torque detection device has a complicated structure and is expensive, and has a problem that it is difficult to mount on a general bicycle or the like. That is, all of the conventional torque detection devices are highly accurate and expensive, such as a strain gauge method and a magnetostriction method, and are suitable for devices that require highly accurate measurement data, for example, for training a bicycle athlete. However, mounting on a general bicycle is difficult in terms of cost, and therefore the appearance of an inexpensive torque detection device is desired.
[0004]
In order to address such a problem, the present applicant has disclosed a sleeve in which a sensor is disposed between an outer periphery of a bearing supporting a crankshaft and an inner periphery of a bearing of a bicycle frame in Japanese Patent Application Laid-Open No. 11-258078. Proposed technology to provide In this technique, although the torque detection device can be configured at a low cost, since the sleeve is disposed on the outer periphery of the bearing, it cannot be mounted on the bicycle unless the shape of the bearing of the frame is changed.
[0005]
Furthermore, the driving torque generated by the driving force of the bicycle is generated at a maximum of 10 kN or more, and a moment is always applied to the crankshaft, and the body frame is deformed by these forces, and the driving torque is not accurately transmitted to the sensor element. . For this reason, it has been difficult to accurately perform measurement with the configuration disclosed in Japanese Patent Application Laid-Open No. 11-258078.
[0006]
An object of this invention is to provide the torque detection apparatus which can be attached to the existing bicycle and can detect a torque.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a torque detector for detecting a driving torque acting on a crankshaft of a bicycle.
A bearing 30 that rotatably supports the crankshaft 13;
A pressure sensor 40;
A first fixing member 37 for fixing one end of the bearing portion 30 in the support portion 21 of the vehicle body frame 12;
From the bearing portion 30 that is attached to the other end of the bearing portion 30 and is displaced with the displacement of the other end of the bearing portion 30 due to the driving torque acting on the crankshaft 13 to hold the pressure sensor 40. A displacement member 38 having a holding portion 38c formed with a small diameter,
A second fixing member 36 that includes a contact portion 36c that contacts the sensor 40, is fixed in the support portion 21 of the vehicle body frame 12, and restricts axial movement of the bearing portion 30 and the displacement member 38. It is a technical feature to have.
[0008]
In the first aspect, one end of the bearing portion 30 is fixed in the support portion 21 of the vehicle body frame 12 by the first fixing member 37, and the displacement member 38 is attached to the other end of the bearing portion 30. The axial movement of the bearing portion 30 and the displacement member 38 is restricted by the second fixing member 36. The other end of the bearing portion 30 is displaced due to the driving torque acting on the crankshaft 13, and the displacement member 38 is displaced accordingly. The pressure sensor 40 attached to the displacement member 38 contacts the contact portion 36c of the second fixing member 36 due to the displacement, and detects the drive torque applied to the crankshaft 13 corresponding to the displacement amount.
Here, the pressure sensor 40 is attached to the holding portion 38 c of the displacement member 38 formed to have a smaller diameter than the bearing portion 30. In other words, since the pressure sensor 40 is not disposed on the outer periphery of the bearing portion 30, the torque detection device fits in the same diameter as the bearing portion 30 and is accommodated in the support portion 21 of the vehicle body frame 12 used in an existing bicycle. It becomes possible.
Furthermore, since it is difficult to be affected by the deformation of the vehicle body frame 12, the torque can be accurately detected.
[0009]
In the second aspect, the radial side wall 38 b of the displacement member 38 is in contact with the side wall 36 d of the second fixing member 36 via the bearing 48. Therefore, the torque can be accurately detected without being affected by the friction between the side wall 38b of the displacement member 38 and the side wall 36d of the second fixing member 36.
[0010]
In the third aspect, the upper surface 36 d and the lower surface 36 e of the holding portion 38 c of the displacement member 38 are in contact with the second fixing member 36 via a bearing 48. For this reason, it is possible to accurately detect the torque without being affected by the friction caused by the pedaling force when the pedal is stroked.
[0011]
In the fourth aspect, the pressure sensor 40 is in contact with the contact portion 36 c of the second fixing member 36 via the spherical contact member 42 disposed on the top. For this reason, transmission of the drive torque to the sensor becomes point contact, and the influence of movement of the load point due to elastic deformation is reduced.
[0012]
In the fifth aspect, the urging member 44 for pressing the pressure sensor 40 against the abutting portion 36 c of the second fixing member 36 is provided. That is, since the preload is applied to the pressure sensor 40 and the transmission point of the driving torque is fixed, the measurement can be performed accurately. Furthermore, when the pedal is stroked, the pressure sensor 40 does not move away from the contact portion 36c of the second fixing member 36, and noise due to repeated contact can be prevented.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a bicycle according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 10 is a bicycle front wheel, 11 is a rear wheel, 12 is a body frame, 13 is a crankshaft (drive shaft), 14 is a crank arm, 15 is a drive sprocket driven by the crankshaft 13, and 16 is a rear axle. , 17 is a driven sprocket provided on the rear axle 16, 18 is a chain spanning the drive sprocket 15 and the driven sprocket 17, and 19 is an indicator installed on the handle.
[0014]
As shown in detail in FIG. 2, the body frame 12 is provided with a hollow cylindrical support portion 21 through which the crankshaft 13 is inserted, and a bearing that supports the crankshaft 13 in a support hole 21 </ b> A of the support portion 21. 30 are accommodated. The crankshaft 13 is rotatably supported in the outer casing 30 a of the bearing 30 via bearings 32 and 34.
[0015]
The end (left end) of the bearing 30 opposite to the drive sprocket 15 is fixed to the support hole 21 </ b> A of the support portion 21 via the left adapter 37. That is, the screw 21a is formed on the left inner periphery of the support hole 21A, and the screw 37a of the left adapter 37 is screwed to the screw 21a. A left lid 46 </ b> A is fitted in the central opening of the left adapter 37.
[0016]
On the other hand, a housing 38 is attached to the end (right end) of the bearing 30 on the drive sprocket 15 side. The housing 38 is formed with a recess 38 a for fitting the end of the bearing 30, a side wall 38 b, and a holding portion 38 c formed with a smaller diameter than the bearing 30. A sensor chip 40 is attached to the holding portion 38c.
[0017]
A right adapter 36 having a through hole 36b in the center is disposed on the outer peripheral side of the holding portion 38c of the housing 38. On the inner periphery of the right adapter 36, a contact portion 36c is formed on which the contact member 42 attached to the top of the sensor chip 40 contacts. A compression spring 44 is disposed at the opposite end of the abutting portion 36c across the crankshaft 13, and a preload is applied by pressing the sensor chip 40 against the inner periphery of the right adapter 36. The axial movement of the bearing 30 and the housing 38 described above is restricted by the right adapter 36. A screw 21a is formed on the right inner periphery of the support hole 21A, and the screw 36a of the right adapter 36 is screwed into the screw 21a. A right lid 46 </ b> B is fitted in the central opening of the right adapter 36.
[0018]
The attachment of the bearing 30, the left adapter 37, the housing 38, and the right adapter 36 will be described with reference to FIG.
First, the bearing 30 is inserted into the support hole 21A of the support portion 21 (FIG. 3A). Next, the right end of the bearing 30 is fixed by screwing the screw 37a of the left adapter 37 into the screw 21a on the left inner periphery of the support hole 21A (FIG. 3B). Here, it is preferable to insert a collar (not shown) between the left adapter 37 and the bearing 30. Then, first, the housing 38 is inserted from the right side of the support hole 21A, the screw 36a of the right adapter 36 is screwed into the screw 21a on the right inner periphery of the support hole 21A, and the right adapter 36 is fixed (FIG. 3 ( C)).
[0019]
In the present embodiment, the left adapter 37 fixes the left end of the bearing 30 in the support hole 21 </ b> A of the vehicle body frame 12, and the housing 38 is attached to the right end of the bearing 30. The axial movement of the bearing 30 and the housing 38 is restricted by the right adapter 36. The right end of the bearing 30 is deviated by the driving torque acting on the crankshaft 13 (elastic deformation), and the housing 38 is deviated accordingly. The sensor chip 40 attached to the housing 38 comes into contact with the contact portion 36c of the right adapter 36 due to the displacement, and detects the driving torque applied to the crankshaft 13 corresponding to the displacement amount.
[0020]
Here, the sensor chip 40 is attached to the holding portion 38 c of the housing 38 that has a smaller diameter than the bearing 30. That is, since the sensor chip is not disposed on the outer periphery of the bearing 30, the torque detection device can be accommodated in the support hole 21A of the body frame used in the existing bicycle and fit in the same diameter as the bearing 30. Become.
[0021]
Here, the principle of detection of the drive torque by the sensor chip 40 will be described with reference to FIG. When the drive sprocket 15 is rotated by stepping on the pedal of the crank arm 14 with the depression force K, a reaction force S is generated in the bearing 30 due to the chain tension T in the chain 18. This reaction force causes the right end of the bearing 30 (see FIG. 2) to bend, and the housing 38 is displaced due to the deflection of the bearing 30 to press the sensor chip 40 toward the right adapter 36, causing mechanical distortion in the sensor chip 40. The electrical resistance of the sensor chip 40 changes according to this distortion. In the present embodiment, the sensor chip 40 is positioned horizontally from the center of the crankshaft. However, it can be arranged by shifting by an angle θ as disclosed in JP-A-11-258078.
[0022]
In the torque detection device according to the present embodiment, a bearing is disposed so as to reduce friction between the housing 38 and the right adapter 36. This configuration will be described with reference to FIGS.
FIG. 5A is a cross-sectional view taken along the line BB of FIG. 2, and the housing 38 shown in FIG. 4 is shown rotated 90 degrees. FIG. 5D is a cross-sectional view along the line DD in FIG. As shown in FIG. 4, a roller bearing 48 held by the retainer 47 is interposed between the upper end surface 38 d and the lower end surface 38 e of the holding portion 38 c of the housing 38 and the through hole 36 b of the right adapter 36. That is, as described above, when the pedal of the crank arm 14 is stepped on with the depression force K, a force to press the housing 38 downward against the right adapter 36 is generated. The reaction force detection is not affected. Here, the roller bearing 48 is used, but it is also possible to interpose a ball bearing 49 via a retainer 47 as shown in FIG.
[0023]
FIG. 5C is a cross-sectional view taken along the line CC in FIG. As shown in FIGS. 5C and 2, a ball bearing 48 is disposed on the side of the right side surface 38 b of the housing 38 via a retainer 47. That is, the left end surface 36 d of the right adapter 36 is in contact with the side wall 38 b of the housing 38 described above via the ball bearing 48. As described above with reference to FIG. 3C, the housing 38 is pressed by the right adapter 36 when the torque detection device is assembled to the bicycle. For this reason, by interposing the ball bearing 48, the contact resistance between the left end surface 36d of the right adapter 36 and the side wall 38b of the housing 38 is not affected by the reaction force detection by the sensor chip 40.
[0024]
As described above with reference to FIG. 2, the compression spring 44 is disposed at the opposite end of the abutting portion 36 c with which the sensor chip 40 abuts across the crankshaft 13, and the sensor chip 40 is attached to the sensor chip 40. Preload is applied by pressing against the inner periphery of the right adapter 36. That is, since the preload of 100 N or less is applied to the sensor chip 40 and the transmission point of the drive torque is fixed, it can be measured accurately. Further, when the pedal is stroked, the sensor chip 40 does not move away from the contact portion 36c, and abnormal noise due to repeated hitting can be prevented.
[0025]
Here, when the sensor chip 40 is deviated as shown in FIG. 6B with the preload applied, the contact point of the contact member 42 and the right adapter 36 generated when the preload is applied changes the initial displacement, The force detected by the sensor chip 40 is (tension reaction force−preload change). In addition, when the tension load is released, the magnitude of the preload between the two parts becomes the frictional force when the elastically deformed part tries to return to its original state, so that it does not return to the initial position and the output at no load changes. To do. For this reason, it is necessary to suppress the preload to 100 N or less which does not affect the position change.
[0026]
Instead of the compression spring 44, as shown in FIG. 5B, an elastic member such as rubber 144 may be interposed to generate preload.
[0027]
Furthermore, in this embodiment, as shown in FIG. 6A, a hemispherical contact member 42 is attached to the top of the sensor chip 40 and is in contact with the contact portion 36c. That is, transmission of driving torque to the sensor chip 40 becomes point contact, and the influence of movement of the load point due to elastic deformation is reduced. On the other hand, as shown in FIG. 6B, if the hemispherical contact member 42 is not disposed on the sensor chip 40, it will come into contact with one another and cause the end of the sensor chip 40 to be lost.
[0028]
As will be described in detail later, the sensor chip 40 is made of a functional ceramic having a characteristic that the electric resistance changes according to mechanical strain. The sensor chip 40 is connected to a load detection circuit 50 and detects the load applied to the sensor chip 40 by the load detection circuit 50 based on the resistance change. As the sensor chip 40, for example, a functional ceramic described in Japanese Patent Application No. 8-205320 is suitable. The functional ceramic has a characteristic that the resistance value between the electrodes (pressure-sensitive part) decreases when a pressure is applied, and this is detected as a voltage to obtain the pressure.
[0029]
Here, the configuration of the load detection circuit 50 using the sensor chip 40 will be described with reference to FIG.
The sensor chip 40 includes a pair of detection units (R + ΔR) and a dummy resistor R connected to one of the detection units. Here, ΔR indicates a resistance change due to the reaction force S. On the other hand, the load detection circuit 50 is provided with a pair of fixed resistors r and r, and constitutes a bridge with the detection part of the sensor chip 40. Here, when the constant voltage V is applied, a potential represented by the following equation is generated as the bridge output e.
[Expression 1]
e = {[R / (R + r)]-(R + ΔR) / [(R + ΔR) + r]} × V
The reaction force S can be obtained from this output potential e.
[0030]
FIG. 8 is a block diagram for calculating drive torque from the load detected by the load detection circuit 50 and calculating and displaying energy consumption from this drive torque. An analog signal corresponding to the load detected by the load detection circuit 50 is converted into a digital signal by the A / D conversion circuit 54 and added to the CPU 52. The ROM 56 stores a program for calculating drive torque and energy consumption based on the detected load, and the RAM 58 has a work area used for calculation. Then, necessary signals are exchanged between the ROM 56 and RAM 58 and the CPU 52, and driving torque and energy consumption are calculated. The calculated energy consumption is displayed on the display device 19.
[0031]
The program in the ROM 56 includes a main program and a timer interrupt routine. The timer interrupt routine starts an interrupt at regular time intervals (for example, every 10 msec) and samples a load signal (resistance or voltage) detected by the load detection circuit 50. On the other hand, the main program integrates the load signal sampled by the timer interruption routine every unit time to calculate the driving torque, and further calculates the energy consumption from the driving torque using the energy consumption conversion formula, and the display device 19 To display. In addition to the energy consumption, the display 19 can also display the driving torque obtained by time integration.
[0032]
Next, the operation of the device of the present invention configured as described above will be described. As shown in FIG. 4, when the pedal of the crank arm 14 is depressed with the depression force K to rotate the drive sprocket 15, a reaction force S is generated in the bearing 30 due to the chain tension T in the chain 18. The reaction force causes the right end of the bearing 30 to bend, and mechanical distortion occurs in the sensor chip 40 in response to the bending, and the electrical resistance of the sensor chip 40 changes in response to the distortion.
[0033]
That is, in the state where the driving torque is not applied to the bicycle, only the above-described preload is applied to the sensor chip 40, and the electrical resistance value of the sensor chip 40 is increased. When drive torque (drive reaction force) acts, the load acting on the sensor chip 40 increases as the drive torque increases, and the electrical resistance value of the sensor chip 40 decreases in inverse proportion to the increase in load. Accordingly, the driving torque acting on the bicycle can be measured based on the change in the electrical resistance of the sensor chip 40.
[0034]
The timer interrupt routine starts an interrupt at regular time intervals, samples the load signal detected by the load detection circuit 50, and the main program time-integrates the load signal sampled by the timer interrupt routine to obtain a driving torque. Further, energy consumption is calculated based on this driving torque and displayed on the display device 19.
[0035]
In this embodiment, it is not necessary to provide a flexible part for attaching a strain gauge for detection, and it is difficult to be affected by temperature changes, so that the apparatus can be configured robustly. Therefore, stable torque detection can be performed over a long period of time even when applied to a bicycle or the like used under severe conditions such as rainwater or hot weather. By realizing such a torque detection device, it is possible to easily obtain the energy consumption required for driving the bicycle, which can contribute to health maintenance and diet.
[0036]
In the above-described configuration, the bearing is used to reduce the friction between the right adapter 36 and the housing 38. However, instead of this, a part sealed with air or liquid can be incorporated into the bicycle frame. is there.
[0037]
In addition to the above-mentioned energy consumption display, the above-described torque detection device travels on an exercise bike for detecting the torque of an electrically assisted bicycle that assists the operation force of the crank pedal electrically or for indoor training. It can also be used to detect the torque of bicycles that cannot be obtained. In the above-described embodiment, the example in which the torque detection device is applied for bicycle torque detection has been described. However, the torque detection device can be applied to a machine tool or the like in addition to the bicycle.
[0038]
【The invention's effect】
As described above, according to the present invention, the sensor chip is attached to the holding portion of the housing formed with a smaller diameter than the bearing. That is, since the sensor chip is not disposed on the outer periphery of the bearing, the torque detection device can be accommodated in the support hole of the body frame used in an existing bicycle, and can be accommodated in the same diameter as the bearing. Furthermore, since the driving torque is detected by the sensor chip having the characteristic that the electric resistance changes according to the mechanical strain, it is very simple and low cost, but is robust and long-term. There is an effect that stable torque detection can be performed.
[Brief description of the drawings]
FIG. 1 is an external view showing a bicycle according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIGS. 3A, 3B, and 3C are explanatory diagrams of assembly of the torque detection device to a bicycle.
FIG. 4 is an explanatory diagram showing a force applied to a sensor chip.
5A is a cross-sectional view taken along the line BB of FIG. 2, FIG. 5B is a cross-sectional view illustrating a modification of FIG. 5A, and FIG. FIG. 5D is a cross-sectional view taken along the line DD of FIG. 5A, and FIG. 5E is a cross-sectional view illustrating a modification of the FIG. 5D.
6A and 6B are explanatory diagrams showing forces applied to the sensor chip. FIG.
FIG. 7 is a circuit diagram showing a circuit configuration of a sensor chip.
FIG. 8 is a block diagram showing a configuration for calculating energy consumption.
[Explanation of symbols]
10 Front wheel 11 Rear wheel 12 Body frame 13 Crankshaft (drive shaft)
14 Crank arm 15 Drive sprocket 16 Rear axle 17 Drive sprocket 18 Chain 19 Display 21 Support portion 21A Support hole 21a, 21b Screw 30 Bearing 30a Outer casing 32, 34 Bearing 36 Left adapter 36a Screw 36b Through hole 36c Contact portion 36d Left end Surface 36e Lower end surface 36d Upper end surface 37 Right adapter 37a Screw 38 Housing 38a Recess 38b Side wall 38c Holding portion 40 Sensor chip 42 Contact member 44 Spring 46A Left lid 46B Right lid 48 Bearing 50 Load detection circuit 52 CPU
54 A / D conversion circuit 56 ROM
58 RAM

Claims (5)

In a torque detection device for detecting drive torque acting on a bicycle crankshaft,
A bearing portion for rotatably supporting the crankshaft;
A pressure sensor;
A first fixing member for fixing one end of the bearing portion in the support portion of the vehicle body frame;
It is attached to the other end of the bearing portion, and is displaced with the displacement of the other end of the bearing portion due to the driving torque acting on the crankshaft, and is formed with a smaller diameter than the bearing portion for holding the pressure sensor. A deflection member having a holding part;
A contact portion that contacts the sensor; and a second fixing member that is fixed in the support portion of the vehicle body frame and restricts axial movement of the bearing portion and the displacement member. Torque detection device. The torque detection device according to claim 1, wherein a radial side wall of the displacement member is in contact with a side wall of the second fixing member via a bearing. The torque detection device according to claim 1 or 2, wherein an upper surface and a lower surface of the holding portion of the displacement member are in contact with the second fixing member via a bearing. 3. The torque detection device according to claim 1, wherein the pressure sensor is in contact with a contact portion of the second fixing member via a spherical contact member disposed on a top portion. 5. The torque detection device according to claim 1, further comprising an urging member for pressing the pressure sensor against a contact portion of the second fixing member.

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