JPH0743227A - Method for calibrating torque sensor - Google Patents

Abstract

PURPOSE:To calibrate the output value of a torque sensor with high accuracy by using the line connecting a torque-output characteristic point set through a first process and a torque-output characteristic point measured during a second process as the output characteristic of the torque sensor. CONSTITUTION:A torque sensor 1 is constituted of a magnetostriction film 3 which is formed on the outer periphery of the output shaft 2 of an internal combustion engine so as to detect the torque generated against the shaft 2 and a magnetic head 4 which detects the magnetizing state of the film 3. The sensor 1 is mounted on a vehicle while the sensor 1 is connected to the combustion engine. When the engine is stopped, no torque is applied to the shaft 2 and the shaft 2 is released from the torque T0 applied to the film 3 at the time of forming the film 3 and the film 3 is strained due to the restoring force of the shaft 2. The output V0 of the sensor 1 is measured in a state where the output torque of the combustion engine is '0' and a torque-output characteristic line connecting the point at which the torque is (T0, 0) and another point at which the output of the sensor 1 is (0, V0) is set. The output torque T of the combustion engine is detected by correlating the output of the sensor 1 during the operation of the combustion engine with the torque-output characteristic line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of calibrating a torque sensor, and more particularly, to an output characteristic of a non-contact magnetostrictive torque sensor having a magnetostrictive film formed on the output shaft of the internal combustion engine to detect the output torque of the internal combustion engine. The present invention relates to a method of calibrating a torque sensor.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting an output torque of an internal combustion engine, a device for detecting a twist of an output shaft of the internal combustion engine and converting it into an output torque is known. The output shaft of the internal combustion engine is a shaft that transmits the output torque generated in the internal combustion engine to the drive wheels, and the output shaft of the internal combustion engine focuses on the fact that a twist according to the output torque occurs in the rotation direction.

In this case, as a mechanism for detecting the twist of the output shaft, a non-contact magnetostrictive system in which a film made of a magnetostrictive material is formed on the output shaft and the magnetic force generated on the surface of the film is detected using a magnetic head or the like. Torque sensors are known. Magnetostrictive material
Since the magnetized state is changed according to the applied strain, the twisted state of the output shaft is to be detected based on the magnetic force generated from the film (hereinafter referred to as a magnetostrictive film).

In such a torque sensor, the voltage signal output from the magnetic head may vary with respect to the magnetic intensity generated by the magnetostrictive film depending on the matching between the output shaft and the magnetic head. Further, due to the difference between the environmental temperature when forming the magnetostrictive film on the output shaft of the internal combustion engine and the environmental temperature when using as a torque sensor,
The output characteristics may change due to temperature distortion.

Therefore, when the torque sensor having such a structure is used, the zero adjustment of the torque sensor is generally executed after the magnetic head is completely assembled. For example, Japanese Utility Model Laid-Open No. 60-163334 discloses a torque detection device that performs such zero point adjustment during no-load operation of an internal combustion engine.

That is, when the internal combustion engine is operating at a constant speed such as in an idling state, or when it is stopped, it is noted that the output shaft is hardly distorted, and in this state, the voltage signal generated from the magnetic head is generated. Output torque "0"
It is grasped as an output signal at time, that is, a zero point signal. Then, the output characteristic of the torque sensor is calibrated with reference to the zero point signal to absorb the quality variation.

As described above, when the output characteristics of the torque sensor are calibrated when the internal combustion engine is stopped, the output voltage of the magnetic head when the output torque is "0" can be reliably detected as a zero point signal. It is possible to calibrate the torque sensor without providing a special calibration step above.

[0008]

However, the above-described conventional method for calibrating a torque sensor is effective when the straight lines representing the torque-output characteristics of the torque sensor fluctuate in parallel, but when the inclination fluctuates. Cannot calibrate its fluctuations.

On the other hand, the film pressure, density, etc. that determine the characteristics of the magnetostrictive film are usually slightly changed during mass production under delicate condition settings. Also, regarding the output shaft, it is not always easy to mass-produce uniform output shafts because of problems such as fluctuations in the material composition ratio and processing accuracy. That is, in the torque sensor having the above configuration, the inclination of the straight line representing the torque-output characteristic changes relatively easily with the characteristic changes of the magnetostrictive film and the output shaft.

Therefore, in the calibration method in which only the zero point adjustment is executed like the above-mentioned conventional torque sensor calibration method, only a part of the characteristic variation that occurs during mass production is calibrated, which is not always appropriate. It was not possible to carry out such a proofreading.

The present invention has been made in view of the above-mentioned points, and a magnetostrictive film which makes the sensor output "0" is formed in a state where a known torque T ₀ is applied to the output shaft, and the output torque is A method for calibrating a torque sensor that can solve the above problems by detecting the sensor output V ₀ when the value is “0” and setting the torque-output characteristic straight line of the torque sensor based on these two torque-output characteristic points. The purpose is to provide.

[0012]

FIG. 1 shows a principle diagram of a method for calibrating a torque sensor which achieves the above object. That is, as shown in FIG. 1, the purpose is to calibrate the output characteristics of a non-contact magnetostrictive torque sensor in which a magnetostrictive film is formed on the output shaft of the internal combustion engine in order to detect the output torque of the internal combustion engine. In the calibration method according to claim 1, the magnetostrictive film is formed in a state in which a known torque T ₀ is applied to the output shaft of the internal combustion engine, and the output of the torque sensor when the torque T ₀ is applied to the output shaft. Is set to 0, and the output V _{0 of the} torque sensor when the torque applied to the output shaft is 0 while the internal combustion engine is stopped.
In the second process A2, the torque-output characteristic point (T ₀ , 0) set in the first process A1, and the torque-output characteristic point (0, V) measured in the second process A2. _This is achieved by a method of calibrating the torque sensor, which is performed by performing a third process A3 in which a straight line connecting the line ( ₀ ) and the output characteristic of the torque sensor is used.

Further, there is provided a torque sensor calibration method for calibrating the output characteristics of a non-contact magnetostrictive torque sensor in which a magnetostrictive film is formed on the output shaft of the internal combustion engine to detect the output torque of the internal combustion engine. A part of the magnetostrictive film is formed in a state where a known torque T ₁ is applied to the output shaft of the internal combustion engine, and a first region where the output becomes 0 when the torque T ₁ is applied to the output shaft is formed. a first processing B1 provided, another portion of the magnetostrictive film, the formed while applying a known torque T ₂ to the output shaft of the internal combustion engine, when the torque T ₂ applied to the output shaft A second process B2 in which a second region where the output is 0 is provided, and the output of the torque sensor in the first region when the torque applied to the output shaft is 0 while the internal combustion engine is stopped. A third process B3 for measuring V ₁ , and
A fourth process B4 of measuring the output V _{2 of the} torque sensor in the second region when the torque applied to the output shaft is 0 while the internal combustion engine is stopped, and the first and second processes Known torque T used in the processes B1 and B2
_1, and T _2, the third and on the basis of the output V _1, V ₂ measured in the fourth processing _{B3, B4, V = V i} + (| V 2 -V 1 | / | T 2 -T _A method of calibrating the torque sensor is also effective in which the fifth process B5 in which the straight line of ₁ |) * T is used as the torque-output characteristic in the i-th region of the torque sensor is executed.

Further, there is provided a non-contact magnetostrictive torque sensor having a magnetostrictive film formed on the output shaft of the internal combustion engine to detect the output torque of the internal combustion engine, the noncontact magnetostrictive torque sensor corresponding to a specific rotational angle position of the output shaft. A torque sensor provided with a plurality of magnetostrictive films formed in a state where different known torques are applied to the output shaft is suitable for carrying out the above-mentioned calibration method and is also useful as a rotation angle sensor for the output shaft.

[0015]

In the method for calibrating a torque sensor according to the present invention, the magnetostrictive film formed in the first process A1 is brought into a neutral state when the torque T ₀ is applied to the output shaft, and the output When no torque is applied to the shaft, a magnetization state equal to that in which a torque of −T ₀ is applied to the magnetostrictive film is exhibited. In the second processing, the torque sensor output when the magnetostrictive film is in such a state is V _0.
To measure.

In this case, the magnetized state of the magnetostrictive film changes according to the applied strain, and as a result, the torque-output characteristic of the torque sensor changes substantially linearly. Therefore, the torque-output characteristic of this torque sensor, that is, the (T, V) characteristic is a straight line that passes through both (T ₀ , 0) and (0, V ₀ ) set in the third processing.

Further, the magnetostrictive film formed in the first region in the first process B1 makes the magnetized state neutral when the known torque T ₁ is applied to the output shaft, The magnetostrictive film formed in the second region in the process B2 has a neutral magnetization state when a known torque T ₂ is applied to the output shaft.

Therefore, when no torque is applied to the output shaft, -T ₁ is applied to the magnetostrictive film in the first region.
A magnetized state equivalent to the state where the torque of 1 is applied appears in the magnetostrictive film in the second region, which is equal to the state where the torque of −T ₂ is applied. And the third
In the fourth process, V ₁ representing the state of the first region and V ₂ representing the state of the second region when no torque is applied to the output shaft in this way are measured. It

On the other hand, the magnetostrictive film formed in the first region and the magnetostrictive film formed in the second region are films formed on the same output shaft under the same conditions, and both regions are formed. The magnetized state of the magnetostrictive film formed in the above-mentioned shows substantially the same rate of change with respect to the change of the torque applied to the output shaft.

That is, the torque-output characteristic formed by the magnetostrictive film in the first region and the torque-output characteristic formed by the magnetostrictive film in the second region are (0, V ₁ ), ( A straight line passing through 0, V ₂ ) and having the same slope is shown. The slope of the straight _{line, "| V 2 -V 1 |} / | T 2 -T 1 |" can be expressed as.

Therefore, the torque-output characteristic of the torque sensor formed by the magnetostrictive film element in the i-th region (i = 1 or 2) is a straight line set in the fifth process, that is, "V = V _i +". _{(| V 2 -V 1 | /} | T 2 -T 1 |)
It becomes a straight line represented by * T ".

By the way, a torque sensor having a plurality of magnetostrictive films formed under different known torques corresponding to a specific rotation angle position of the output shaft, the torque sensor of the torque sensor accompanying the rotation when the output shaft rotates. The output value is changed stepwise. Therefore, by monitoring the fluctuation, it becomes possible to detect the rotation angle of the output shaft.

[0023]

FIG. 2 is a block diagram showing an example of a torque sensor 1 capable of ensuring high detection accuracy by calibrating the output characteristics by applying the torque sensor calibration method according to the present invention. The torque sensor 1 shown in FIG. 2 has an output shaft 2 of an internal combustion engine.
2 is a sensor provided to detect the torque generated on the output shaft 2, and a magnetostrictive film 3 formed on the outer periphery of the output shaft 2 as shown in FIG. 2A, and a magnetic head 4 for detecting the magnetization state of the magnetostrictive film 3. Composed of.

The magnetostrictive film 3 is formed of an amorphous thin film such as Fe-Si-B known as a giant magnetostrictive material. Therefore,
When the output shaft 2 is distorted by external stress, the magnetostrictive film 3
A magnetized state corresponding to the generated strain will appear on the surface of the.

The output shaft 2 is a member that is connected to a crank shaft of an internal combustion engine (not shown) and transmits the output torque generated in the internal combustion engine to the transmission. During operation of the internal combustion engine, the output shaft 2 rotates in the direction of rotation of the internal combustion engine. Torsional moment is generated according to the output torque of.

In this case, if the output torque of the internal combustion engine acts in the direction indicated by "T" in FIG. 2 (A), the stress in the direction indicated by ± σ in the figure is applied to the output shaft 2. When the magnetostrictive film is divided into A to D regions as shown in FIG. 2B, compressive stress acts on the A and D regions and tensile stress acts on the B and C regions. Then, the magnetostrictive film 3
On the surface of, the magnetized state is divided into two regions, A and D regions and B and D regions.

The magnetic head 4 described above is provided to detect such a change in the magnetization state.
As shown in (A) and (B), a U-shaped conductor 4a arranged parallel to the longitudinal direction of the output shaft 2 and a U-shaped conductor 4b arranged parallel to the radial direction of the output shaft. And the AC magnetic field generation circuit 4c and the magnetic field detection circuit 4 respectively incorporated therein.
d and.

That is, when an AC magnetic field is applied to the conductor 4a by the AC magnetic field generating circuit 4c, the generated magnetic force lines flow in the closed loop composed of the conductor 4a and the magnetostrictive film 3. At this time, if the magnetostrictive film 3 exhibits a uniform magnetic resistance, the conductor 4b faces the magnetostrictive film 3 at two points due to the symmetry (FIG. (B)).
(Indicated by a black square in the figure), the magnetic potential is always the same and the conductor 4b
There is no magnetic flux flowing inside.

However, if the magnetization state is non-uniform due to the stress of ± σ as described above, naturally the magnetic potentials at the two points where the conductor 4b faces the magnetostrictive film 3 are different. Then, the difference in magnetic potential fluctuates with the change in the magnetic field strength generated by the conductor 4a, and eventually an alternating magnetic field is generated in the conductor 4b.

Therefore, when the amplitude of the magnetic flux density flowing through the conductor 4b is detected, the amplitude indicates the non-uniformity of the magnetized state of the magnetostrictive film 3, that is, the magnitude of the torque T transmitted to the output shaft 2. It will be.

That is, when the magnetic field detection circuit 4d incorporated in the conductor 4b is realized by a pickup coil for converting the magnetic field strength flowing in the conductor 4b into a current value, the equivalent circuit of the torque sensor 1 is shown in FIG. The output torque of the internal combustion engine can be represented by the current value detected by the magnetic field detection circuit 4d.

In the torque sensor 1 having such a structure, the sensor output V varies in the unloaded state due to the residual stress when the magnetostrictive film is formed, and the hardness error of the output shaft 2 and the magnetostrictive film 2 are generated. As described above, the output change rate with respect to the torque fluctuation varies due to the characteristic error of the above.

The torque sensor calibration method of the present embodiment is characterized in that these variations are absorbed and an appropriate torque-output characteristic is always set, and the output torque of the internal combustion engine can be detected with high accuracy. have. The procedure of the calibration method of this embodiment will be described in detail below.

FIG. 3 is a conceptual diagram for explaining a film forming process for forming the magnetostrictive film 3 on the output shaft 2. The torque sensor 1 of this embodiment employs a method of forming the magnetostrictive film 3 by sputtering, and the evaporation source 11 (Fe-Si-B) for sputtering and the evaporation source 11 are appropriately provided in the vacuum chamber 10. A motor 12 for rotating, a table 13 having a function of rotating and holding the output shaft 2 as a film-forming substrate at an appropriate angular velocity, and the like are provided.

Further, the vacuum chamber 10 is provided with a quartz window 14 which guides a laser beam from the outside, and the vapor deposition source 11 is excited by a laser beam which is focused by a quartz lens 15 and then enters through the quartz window 14. It is ionized. Then, the excited Fe-Si-B forms a thin film on the surface of the output shaft 2 by the action of the electric field formed between the vapor deposition source 11 and the output shaft 2 by the bias voltage applied to the output shaft 2.

By the way, the table 13 for rotating and holding the output shaft 2 is provided with a rotary motor 13a and a load motor 13b as shown in FIG. The load motor 13b is a motor that feedback-controls the rotational force exerted with reference to the torque detected by the torque detection shaft 13c that holds the output shaft 2.

Therefore, for example, when the torque detection shaft 13c is set to generate a torque of magnitude T ₀ , the output shaft 2 is applied with a torsion torque of T ₀ by the interaction of the rotary motor 13a and the load motor 13b. It will rotate in the state. That is, the magnetostrictive film 3 that does not feel any stress when the output shaft 2 receives the torsion torque of T ₀ is formed on the surface of the output shaft 2.

In this embodiment, the step of forming the magnetostrictive film 3 in the vacuum chamber 10 having the rotary motor 13a and the load motor 13b as described above is the first step.
Corresponding to the process A1.

By the way, when no strain is generated in the magnetostrictive film 3, no output appears in the magnetic head 4 as described above, and the output V of the torque sensor 1 becomes "0".
In other words, the magnetostrictive film 3 formed by such a method.
The output V of the torque sensor 1 including is ₀ when the torque T ₀ is transmitted to the output shaft 2.

On the other hand, when the torque sensor 1 is connected to an internal combustion engine and mounted on a vehicle, no torque is applied to the output shaft 2 if the internal combustion engine is stopped. In this case, the torque T ₀ applied to the magnetostrictive film 3 at the time of formation is released from the output shaft 2, and the magnetostrictive film 3 is distorted due to the restoring force of the output shaft 2. .

Therefore, when the internal combustion engine is stopped, a magnetized state is formed on the surface of the magnetostrictive film 3 due to the release of the torque T ₀ , and the torque sensor 1 responds to the magnetized state. The output V ₀ will be output.

Thus, in the torque sensor 1,
It is guaranteed that the input torque T and the sensor output V both satisfy (T ₀ , 0) and (0, V ₀ ). This V ₀ is a value that varies depending on the hardness characteristics of the output shaft 2 and the output characteristics of the magnetostrictive film 3, and the individual torque sensors 1
The value reflects the characteristics of.

Therefore, in order to realize the second processing, the sensor output V ₀ is measured under the condition that the output torque of the internal combustion engine is "0", and then the third processing is performed as shown in FIG. If the torque-output characteristic straight line passing through (T ₀ , 0) and (0, V ₀ ) is set, the characteristic of the torque sensor 1 is set appropriately.

Therefore, during the operation of the internal combustion engine thereafter, the output V of the torque sensor 1 is measured, and by referring to the characteristic straight line shown in FIG. The output torque T of the internal combustion engine can be detected.

By the way, in the construction method of the torque sensor 1 described above, if the internal combustion engine is stopped, no residual torque exists on the output shaft 2 and no residual magnetization occurs on the magnetostrictive film 3. It is assumed that. That is, when some force is applied between the crankshaft and the transmission while the internal combustion engine is stopped, or the magnetostrictive film 3
If the residual magnetization occurs in ( ₁ ), an inappropriate value may be measured as (0, V ₀ ) measured in the second processing described above.

FIG. 6 shows a torque sensor 21 configured to realize a calibration method capable of canceling the influence of such residual stress.
The perspective view showing the principal part of FIG. This torque sensor 21 is
A first region 3a formed on the magnetostrictive film 3 with a known torque T ₁ applied to the output shaft 2 and a known torque T ₂
And a second region 3b formed in the state of adding.

As a method of forming the first region 3a and the second region 3b on the magnetostrictive film 3, for example, as shown in FIG. 7 (A), an opening adapted to the first or second region is formed. A method of changing the torque applied to the output shaft 2 for each region by using the provided stainless steel mask can be applied.

Further, as shown in FIG. 7B, for example, only the portion corresponding to the second region 3b is formed by forming the magnetostrictive film 3 with the torque T ₁ applied and then applying the torque T _2. It is also possible to form the first and second regions 3a and 3b by heating the substrate with laser light or far infrared rays and performing an annealing treatment. Note that these film forming steps correspond to the above-described first process B1 and second process B2.

In this way, on the same output shaft 2, when the torque T ₁ is applied to the output shaft 2, the first region 3a in which the magnetized state becomes neutral and the torque T ₂ is applied. When the second region 3b in which the magnetization state is neutral is provided,
It is possible to set torque-output characteristics in the first region 3a and the second region 3b, respectively.

That is, focusing on the first region 3a, the torque output V becomes "0" when the torque T ₁ is applied to the output shaft 2, and focusing on the second region 3b, When the torque T ₂ is applied to the output shaft 2, the torque output V becomes “0”. Sensor Then, if the output shaft 2 is not also transmitted any torque, is V ₁ was with respect to the first area 3a, also have V ₂ with respect to the second region 3b, due to the restoring force of the output shaft 2, respectively Appears as output.

[0051] Thus, by connecting the torque sensor 21 to the internal combustion engine, by measuring the respective two sensor outputs V ₁ and V ₂ when the internal combustion engine is in a no-load state, as shown in FIG. 8 (T ₁ , 0) and (0, V ₁ ) through the first region 3
a first characteristic straight line representing a torque-output characteristic relating to a,
A second characteristic straight line, which passes through (T ₂ , 0) and (0, V ₂ ) and represents the torque-output characteristic regarding the second region 3b, can be set.

The step of measuring V ₁ and V ₂ is as follows.
It corresponds to the above-mentioned third process B3 and fourth process B4.

By the way, the first area 3a and the second area 3
b is merely classified according to the torque condition at the time of film formation, and these two torque-output characteristics show only the torque-output characteristics of the magnetostrictive film 3 formed on the same output shaft 2. is there.

That is, regarding the material of the output shaft 2, the processing accuracy, the composition component of the magnetostrictive film 3, the film forming conditions, etc., which affect the inclination of the straight line representing the torque-output characteristic, the second region is also used. There is no great change in the area 3b. Therefore, it can be considered that the first characteristic line and the second characteristic line shown in FIG. 8 have the same inclination but different intercepts on the graph.

Then, the slopes of these two straight lines are the same,
That is, as long as both straight lines are parallel, the inclination ΔV / ΔT
Can be expressed as ΔV / ΔT = | V ₂ −V ₁ | / | T ₂ −T ₁ |.

Further, as long as these two straight lines are parallel to each other, the sensor output value in the no-load state, that is, (0, 0) due to the influence of the residual stress of the output shaft 2 and the residual magnetization of the magnetostrictive film 3.
Even if the measured values of V ₁ ) and (0, V ₂ ) fluctuate, | V ₂ −
V ₁ | is constant.

Therefore, the first characteristic line is V = V ₁ + (| V ₂ −V ₁ | / | T ₂ −T ₁ |) * T (1) and the second characteristic line is The straight line is V = V ₂ + (| V ₂ −V ₁ | / | T ₂ −T ₁ |) * T (2), which indicates the residual stress of the output shaft 2 and the residual magnetization of the magnetostrictive film 3, respectively. It is set as a straight line that is not affected.

Therefore, the output V of the torque sensor 21 is set to the first value.
Of the torque sensor 2 according to the above formula (1), and when its output V is detected on the second region 3b, according to the above formula (2).
The input torque T transmitted to No. 1, that is, the output torque of the internal combustion engine can be appropriately back-calculated.

In this case, the setting process of the equations (1) and (2) corresponds to the above-mentioned fifth process B5, and according to the present method of calibrating the torque sensor based on the characteristic straight line,
It is possible to secure stable calibration accuracy as compared with the method of performing calibration based on the single characteristic straight line shown in FIG.

In this embodiment, the first area 3a
Is larger than the second area 3b, and the sensor output V output when the magnetic head 4 searches the first area 3a and the sensor output V output when the magnetic head 4 searches the second area 3b. The output difference from the sensor output V is monitored, only the output V obtained when the first area 3a is searched is taken in as the effective sensor output V, and the conversion according to the above formula (1) is performed. There is.

By the way, in such a configuration in which the first region 3a and the second region 3b are provided on the magnetostrictive film 3 and the output difference in each region can be detected, the fluctuation of the sensor output is monitored. Thus, it is possible to detect what kind of area the magnetic head 4 is searching. Therefore, if the formation position of each region is made to correspond to the rotation angle of the output shaft 2, the rotation angle of the output shaft can be estimated to some extent from the output value of the torque sensor 21.

FIG. 9 is a side sectional view showing the configuration of the torque sensor 31 devised as a sensor which can be used also as a rotation angle sensor of the output shaft 3 in view of the possibility of the non-contact magnetostrictive torque sensor. In the figure, the same components as those of the torque sensors 1 and 21 described above are designated by the same reference numerals, and the description thereof will be omitted.

As shown in the figure, in the torque sensor 31 of this embodiment, the magnetostrictive film 3 of the above-mentioned torque sensor 21 is the first.
And, while it was divided into the second areas 3a and 3b,
Furthermore, the third region 3c is additionally provided, which is characterized in that it is divided into three regions. This third area 3c is
This is a region where a known torque T ₃ is applied to the output shaft 2 to form a film in order to satisfy the relationship of the third characteristic straight line in FIG. 10.

In the torque sensor 31 having such a structure, the magnetic head 4 is moved to the second →
Each area is searched with the first cycle → the third cycle → the first cycle as one cycle, and the output fluctuation (→→
→ 1 cycle) will be obtained. Here, the solid line in FIG. 11 shows the sensor output when the input torque T transmitted to the output shaft 2 is small, and the broken line in FIG. 11 shows the sensor output when the input torque T rises.

Therefore, the positions where the first to third regions 3a to 3c are formed and the rotation angle of the output shaft 2 are made to correspond appropriately, and for example, as shown in FIG. 11, the rotation angle is near 0 ° (360 °). If the third region is formed near the second region and the rotation angle of 180 °, the rotation angle of the output shaft 2 can be detected in units of about 180 °.

The number of regions formed on the magnetostrictive film 3 is 3
However, when it is necessary to detect the rotation angle more finely, the first to third regions 3a described above are not limited thereto.
A new area may be added to 3c.

In this case, the rotation of the conventional internal combustion engine is detected,
Alternatively, a crank angle sensor, a rotation speed sensor, or the like provided to detect the state of each cylinder may be used as the torque sensor 31.
Can be substituted by

By the way, it is known that the internal combustion engine is stopped while the compression process is being performed in any of the cylinders. Therefore, for example, in a 4-cylinder internal combustion engine, # 1,
The second region 3b is aligned with the specific crank angle during which the piston of the # 4 cylinder moves from the bottom dead center to the top dead center.
Further, if the third region 3c is formed in accordance with the specific crank angle during which the pistons of the # 2 and # 3 cylinders move from the bottom dead center to the top dead center, based on the output of the torque sensor 31, It is possible to detect in which state the internal combustion engine is stopped.

In this case, when restarting the internal combustion engine, it is possible to detect the state of each cylinder while it is stopped, and until the prospective injection to all the cylinders or the cylinder discrimination which has been generally performed is completed. It is also possible to supply fuel only to the appropriate cylinders without executing the fuel cut.

[0070]

As described above, according to the first aspect of the invention, it is ensured that the magnetized state of the magnetostrictive film becomes neutral when a known torque T ₀ is applied to the torque sensor. The sensor output V ₀ when no torque is applied to the output shaft is a value uniquely determined by the restoring force of the output shaft and the output characteristic of the magnetostrictive film.

Therefore, when the internal combustion engine is in a no-load state, no stress is applied to the output shaft, and no residual stress is generated in the magnetostrictive film. By simply measuring the sensor output V ₀ , the data can be secured for two points on the straight line representing the torque-output characteristic of the torque sensor.

Therefore, according to the method of constructing the torque sensor according to the present invention, the torque-output characteristic can be appropriately set for each torque sensor, and compared with the conventional calibration method in which only the zero point adjustment is performed. The output value of the torque sensor can be calibrated with extremely high accuracy.

According to the second aspect of the invention, the output characteristics of the torque sensor are set in consideration of the respective output characteristics of the first region and the second region formed on the magnetostrictive film. To be done. The inclination of the straight line representing the set torque-output characteristic is constant regardless of the presence or absence of residual stress on the output shaft and the presence or absence of residual magnetization of the magnetostrictive film.

Therefore, while the calibration accuracy in the invention described in claim 1 is affected by these residual stress and residual magnetization, the calibration method of the torque sensor according to the present invention is not affected by it. The advantage is that it can always maintain appropriate calibration accuracy.

Furthermore, the invention according to claim 3 is suitable for carrying out the invention according to claims 1 and 2 described above, and as a crank angle sensor capable of detecting the stop position of the internal combustion engine, or a cylinder discrimination sensor. It can also be used as a rotation speed sensor, and can reduce the number of parts of an internal combustion engine and improve startability.

[Brief description of drawings]

FIG. 1 is a principle diagram of a method for calibrating a torque sensor according to the present invention.

FIG. 2 is a diagram for explaining a configuration and an operation of a torque sensor suitable for carrying out a torque sensor calibration method according to an embodiment of the present invention.

FIG. 3 is a schematic view of an apparatus for forming a magnetostrictive film of a torque sensor.

FIG. 4 is a diagram for explaining a method of forming a magnetostrictive film of a torque sensor.

FIG. 5 is a graph showing a straight line representing the torque-output characteristic of the torque sensor set by the calibration method of the present embodiment.

FIG. 6 is a diagram for explaining a configuration of a torque sensor suitable for carrying out a method of configuring a torque sensor according to another embodiment of the present invention.

FIG. 7 is a diagram for explaining a method of forming a magnetostrictive film of the torque sensor of this embodiment.

FIG. 8 is a graph showing a straight line representing the torque-output characteristic of the torque sensor set according to the present embodiment.

FIG. 9 is a front sectional view showing a configuration of a torque sensor according to the present invention.

FIG. 10 is a straight line showing a torque-output characteristic of the torque sensor set according to the present embodiment.

FIG. 11 is a diagram showing a sensor output of the torque sensor of the present embodiment.

[Explanation of symbols]

 A1, B1 First processing A2, B2 Second processing A3, B3 Third processing B4 Fourth processing B5 Fifth processing 1, 21, 31 Torque sensor 2 Output shaft 3 Magnetostrictive film 3a First area 3b Second area 3c Third area 4 Magnetic head 13a Rotary motor 13b Load motor 13c Torque detection shaft

Claims (3)

[Claims] 1. A method of calibrating a torque sensor for calibrating the output characteristics of a non-contact magnetostrictive torque sensor, wherein a magnetostrictive film is formed on an output shaft of the internal combustion engine in order to detect the output torque of the internal combustion engine. A known torque T is applied to the output shaft of the internal combustion engine by using the magnetostrictive film.
_{A first} process in which the output of the torque sensor is set to 0 when the torque T ₀ is applied to the output shaft, the process being performed in a state where ₀ is added; A second process of measuring the output V _{0 of the} torque sensor when the torque applied to the output shaft is 0; a torque-output characteristic point (T ₀ , 0) set in the first process; A method of calibrating a torque sensor, comprising: performing a third process of setting a straight line connecting the torque-output characteristic point (0, V ₀ ) measured in the process of 2 as the output characteristic of the torque sensor. . 2. A torque sensor calibration method for calibrating the output characteristics of a non-contact magnetostrictive torque sensor, wherein a magnetostrictive film is formed on an output shaft of the internal combustion engine to detect the output torque of the internal combustion engine. A part of the magnetostrictive film is formed in a state where a known torque T ₁ is applied to the output shaft of the internal combustion engine, and a first region where the output becomes 0 when the torque T ₁ is applied to the output shaft is formed. a first process of providing the other portion of the magnetostrictive film, formed while applying a known torque T ₂ to an output shaft of the internal combustion engine, when the torque T ₂ applied to the output shaft A second process of providing a second region where the output is 0, and an output V _{1 of the} torque sensor in the first region when the torque applied to the output shaft is 0 while the internal combustion engine is stopped. And a third process for measuring the output shaft during the stop of the internal combustion engine. A fourth processing applied torque measuring the output V ₂ of the torque sensor in the second area when it is 0, known torque T used in the first and second processing
₁ and T ₂ and the outputs V ₁ and V ₂ measured in the third and fourth processes, V = V _i + (| V ₂ −V ₁ | / | T ₂ −T ₁ |) A method of calibrating a torque sensor, characterized in that a straight line * T is subjected to a fifth process of setting a torque-output characteristic in the i-th region of the torque sensor. 3. A non-contact magnetostrictive torque sensor in which a magnetostrictive film is formed on an output shaft of the internal combustion engine to detect the output torque of the internal combustion engine, the non-contact magnetostrictive torque sensor corresponding to a specific rotation angle position of the output shaft. A torque sensor comprising a plurality of magnetostrictive films formed with different known torques applied to the output shaft.