JPH03210444A - Apparatus for compensating zero point of torque sensor - Google Patents

Abstract

PURPOSE:To improve accuracy of zero-point compensation by compensating a zero point of a torque sensor with considering a sensor output and an estimated friction torque, when a transmission is neutral. CONSTITUTION:A neutral detecting means 4 is set so that N, P signals at AT, that is, signals of an inhibitor switch which permits cranking at the time of neutral or in a P range are detected. A sensor output Vi is stored in a storage means 52 while a friction torque VF of an output axis of a transmission is estimated by an estimating means 7 so that the friction torque VF and the sensor output Vi are sent to a compensating means 55. The compensating means 55 compensates the zero point of the torque sensor based on a sum VZ of the above values Vi and VF. That is, a torque signal output value VO such that Vi-VZ=VO is obtained. Thus a fluctuation of the friction torque as time passes during driving can be eliminated so that highly accurate zero-point compensation is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for compensating the zero point of a torque sensor incorporated in a transmission of a vehicle drive system.

(Prior Art) Conventionally, a zero point compensator for a torque sensor includes, for example, a temperature detection section installed near a functional part of the torque sensor, and compensates the temperature characteristics of the torque sensor based on the detection result of this temperature detection section. A device equipped with a temperature compensation coil is known (Japanese Patent Application No. 62-331263).

(Problem to be Solved by the Invention) However, in such a zero point compensation device for a torque sensor, the temperature near the functional part of the torque sensor is detected and the temperature characteristics of the torque sensor are compensated according to the detection result. Because of this configuration, not only a special temperature compensation coil is required, but also the end of the temperature compensation coil is adjusted according to the accuracy variation of each sensor in order to absorb the variation in the accuracy of the zero point set of each sensor. It is necessary to trim and precisely align the zero point. In addition, since the temperature compensation coil cannot cope with fluctuations in the friction torque of the transmission output shaft due to changes over time, there is a problem in that the zero point compensation accuracy of the torque sensor decreases by the amount of the fluctuations.

This invention was made by focusing on such conventional problems, and its purpose is to set the sensor output when the drive system is in neutral, and to adjust the zero point of the torque sensor based on this measurement result. This aims to improve the zero point compensation accuracy of the torque sensor.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a neutral detection means for detecting the neutral state of the transmission in a zero point compensation device for a torque sensor attached to the output shaft of the transmission. , a storage means for storing the sensor output in neutral, an estimation means for estimating the friction torque of the output shaft, and a correction means for correcting the zero point of the torque sensor based on the estimated friction torque and the stored sensor output. , is characterized by what it does.

(Operation) In the present invention, the neutral state of the transmission is detected by the neutral detection means, and the sensor output Vi at this time is stored in the storage means. On the other hand, the friction torque VF of the output shaft of the transmission is estimated by an estimation means, and this friction torque vF and the sensor output Vi are sent to a correction means. In this correction means, the above value V
The zero point of the torque sensor is corrected based on the sum Vz of i and VF. In other words, the torque signal output value Vo is obtained such that Vi-Vz=Vo.

In this way, the zero point correction of the torque sensor is performed based on the sum Vz of the sensor output in the neutral state and the estimated friction torque, so the zero point setting error inherent in the torque sensor is removed, and the friction torque over time during operation is corrected. It is possible to remove the fluctuations in the equation, thereby ensuring highly accurate zero point compensation.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

First, the configuration will be explained. 1 is a vehicle engine, 2 is a transmission (AT), and the transmission 2 is provided with neutral detection means 4 for detecting a neutral state. The neutral detection means 4 is
It is set to detect the N-P signal at the AT, that is, the inhibitor switch signal that allows cranking when in neutral or P range.

A torque sensor 3 is installed between the transmission 2 and the differential gear 8 to detect the torque of the output shaft of the transmission 2. The sensor output value Vi of the torque sensor 3 and the detection signal N of the neutral detection means 4 are both sent to the zero point compensator main body 5. As shown in FIG. 2, the internal structure of the zero point compensator main body 5 includes a correction means (adder) 55 between the human power section and the output section, and a correction means (adder) 55 between the correction means 55 and the human power section. is analog switch edge 51. Storage means 52. A circuit section consisting of an adder 53 and an inverter 54 is connected in parallel. Furthermore, a friction function generator 7 is connected to the adder 53, and this function generator 7
functions as means for estimating the friction torque of the output shaft based on the output shaft rotation speed No. of the transmission 2.

Next, the operation of this embodiment will be explained. Now, when the neutral detection means 4 detects the neutral state of the transmission 2 based on the signal from the inhibitor switch, the neutral signal N is sent to the analog switch 51 of the zero point compensator main body 5, and this switch 51 is turned ON. Then, the output value Vi of the torque sensor 3 is held and stored in the storage means 52. This output value Vi is sent to the adder 53 by
Friction torque VF estimated by the function generator 7
This added output value V2 is then added to the inverter 5.
4 and becomes a negative value -Vz.

Next, this output value -Vz is added to the output value Vi of the torque sensor 3 by the correction means 55, and the result is output as a torque signal output value Vo=Vi-Vz.

According to the zero point set based on this output value Vo, as shown in Fig. 3 (
The characteristic graph is corrected as shown in b). That is, compared to the conventional characteristic graph shown in FIG. 3(a), the zero point is compensated so that the y-intercept is moved in parallel in the -y-axis direction by viVz. As a result, it is possible to eliminate variations in accuracy of zero point setting caused by individual torque sensors themselves.

FIG. 4 shows another embodiment of the present invention, in which a microcomputer 17 with a built-in estimation means 16 is used to perform more accurate zero point compensation. In addition, microcomputer 1
7, as shown in FIG.
, engine oil temperature T, neutral signal N, etc. are manually controlled.

FIG. 6 is a flowchart illustrating the detailed operation of this zero point compensation device. As shown in this figure, the first feature of this example is that after detecting the neutral signal N (step 1)
, after the predetermined time to has elapsed (step 2 is affirmative), the neutral signal N is manually input to the determination section of the microcomputer 7. This is to prevent the influence of signal transmission delay due to oil pressure loss of the AT clutch. If this predetermined time 10 is set to be longer as the temperature T of the engine oil is lower, more accurate detection results can be obtained, but generally it is set to 0.1 to 1.0 seconds after warm-up. When operating at extremely low temperatures, it may be set to 1 to 10 seconds.

The second feature of this example is that the friction torque VF in the neutral state is calculated based on the function graph of the AT output shaft rotation signal NO (Step 3), and this friction torque VF is converted into the output value Vi of the torque sensor 3. The value Vz is obtained by adding the torque signal output value VowVi (step 4).
-Vz was found (step 5). Thereby, it is possible to absorb friction torque fluctuations due to changes over time and improve detection accuracy.

Here, the friction torque VF in neutral refers to the transmitted torque generated by friction called "drag torque" in the neutral state. This friction torque VF is
For example, when a wet multi-disc clutch is used as an oscillation element, it can cause the vehicle to start moving due to racing at low temperatures.

The factors forming the friction torque VF include forward clutch misalignment, clutch gear ratio, transmission input/output shaft rotation speed No. and Ni.

There are friction material properties, oil properties, etc. (N i −N
If o) is positive, it will be a positive torque, and if it is negative, it will be a reverse torque.

The magnitude of this torque varies greatly depending on the gap between the clutch plates and the viscosity of the oil, but since the return of the clutch piston after returning to neutral also varies depending on the viscosity of the oil, it is necessary to perform temperature correction to estimate the friction torque VF. , it will be better.

When calculating the friction torque VF, refer to Fig. 7 (a
) is not limited to the function graph of the output shaft rotation signal No. Depending on the required accuracy, the function graph of the difference (No - Ni) between the output shaft rotation signal No. and the manual shaft rotation signal Ni (see FIG. 7(b)
) may also be used. In this case, it goes without saying that the formulas and constant values of the function graph vary depending on the structure of the AT. Note that the friction torque VF varies greatly depending on the situation, and takes a particularly large value during low-temperature operation. Therefore, in order to obtain more accurate detection results, the rotation signal No.
It is preferable to use a function graph that uses both (Ni) and engine temperature as parameters.

(Effects of the Invention) As described above, according to the present invention, the zero point compensation of the torque sensor is performed in consideration of the sensor output when the transmission is in neutral and the estimated friction torque. The effect of absorbing and eliminating the influence of friction torque fluctuations due to variations and changes over time is obtained, and zero point compensation can be performed more accurately than in the past.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the zero point compensating device for a torque sensor according to the present invention, Fig. 2 is a circuit diagram showing the detailed configuration of the zero point compensating device, and Figs. 3 (a) and (b) respectively. A graph showing the characteristics of the sensor output, Fig. 4 is a block diagram showing another embodiment of the present invention, Fig. 5 is a main part configuration diagram of the microcomputer that controls the operation of the zero point compensation device body, and Fig. 6 shows the zero point compensation. A flowchart explaining the operation of the device, and FIGS. 7(a) and 7(b) are characteristic graphs of friction torque, respectively. 2...Transmission 3...Torque sensor 4...Neutral detection means 5...Zero point compensation device body 55...Correction means 7...Friction torque function generation means (estimation means) 16...Estimation Means 17...Microcomputer

Claims (1)

[Claims] 1. A zero point compensation device for a torque sensor attached to an output shaft of a transmission, comprising: neutral detection means for detecting a neutral state of the transmission; storage means for storing a sensor output in neutral; A zero point compensating device for a torque sensor, comprising: estimating means for estimating friction torque; and correcting means for correcting the zero point of the torque sensor based on the estimated friction torque and the stored sensor output.