JPH01109170A - Control device for torque - Google Patents

Abstract

PURPOSE:To incorporate a device into a unit and improve reliability by forming a sensor for detecting torque transmitted along a rotary shaft and a circuit for controlling auxiliary torque in accordance with the detected torque in a body and installing same on a fixing member holding the rotary shaft. CONSTITUTION:Steering torque given to a steering wheel shaft 1 is transmitted to a pinion shaft 2 via a torsion bar 8 rotating a pinion 3 while sliding a rack shaft 4 to carry out steering. On the other hand, the torque of a motor 5 is transmitted from a pinion 6 to the pinion shaft 2 via a bevel gear 7 to give auxiliary steering force. In such a structure, magnetic drums 9, 10 are provided on the bottom end of the steering wheel shaft 1 and the top end of the pinion shaft 2 respectively. Also, a magnetic resistance element 11 which, together with the magnetic drums 9, 10 forms a noncontact type torque sensor is integrally formed with a control unit U. The control unit U is installed on a sensor holding portion 20.

Description

[Detailed description of the invention] [Industrial application field] In accordance with the present invention) t, C, depending on the torque applied to the rotating shaft.

The present invention relates to a torque control device that can increase torque in a direction that assists this, and particularly relates to a torque control device suitable for an electric power steering system for an automobile.

[Conventional technology]

K to reduce driver fatigue and increase safety.

The application of so-called power steering has become quite common in steering systems for automobiles and other vehicles.

Conventionally, hydraulically operated systems have been the mainstream for this system.

However, in recent years, so-called electric power steering systems, which use an electric actuator such as an electric motor as a source of auxiliary steering force, have been widely adopted from the standpoint of equipment in the engine room and enrichment of control contents. It is in.

By the way, in order to fully utilize the advantage that this electric power steering device can be easily installed in a cabin, it is desirable to unitize it as much as possible.

Therefore, in the conventional device, as described in Japanese Patent Laid-Open No. 57-47251, an electric motor for generating auxiliary steering force and its control circuit unit are integrated.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the installation of a torque detection sensor or the heat generation of the electric motor.

There were problems such as reduced reliability due to the presence of connectors and wiring leads between the sensor and control circuit unit, the use of additional elements to maintain noise resistance, and measures to prevent temperature rise in the control circuit unit.

The purpose of the present invention is to avoid problems in reliability, noise resistance, heat resistance, etc. associated with unitization, to achieve sufficient miniaturization, and to provide torque that is easy to install and to be applied to electric power steering devices for automobiles. The purpose is to provide a control device.

[Means for solving problems]

The above object is achieved by making the torque detection sensor non-contact and integrating the sensor and the control circuit unit.

[Function] - Since the sensor and control circuit unit are integrated, there is no need for external wiring leads or connectors between them, and there is almost no risk of picking up noise, thus improving noise resistance. No special consideration is required, and since the control circuit unit is not in contact with the motor, there is no problem with heat resistance, and sufficient reliability can be easily obtained.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the torque control device according to the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a rack-and-pinion electric power steering system for automobiles, where 1 is a handle shaft, 2 is a pinion shaft, 3 is a pinion, 4 is a rack shaft, 5 is an electric motor, 6 is a pinion, 7 is a bevel gear, 8 is a torsion bar, and 9 and 10 are magnetic drums for torque sensors.

11 is a magnetoresistive element for a torque sensor, 12 is a circuit board, 13 is various control circuit elements including a one-chip microcomputer, and 14 is a pary-FET for switching.

15 is a heat sink, 16 is an internal connection lead, 17 is a connector, 2 (H-1 sensor holding part, 21 is a motor holding part, 22
is the rack holding part, 23 to 26 are the bearings, 27, 2
8 is an oil seal, 29 is a dust seal, and S.

A steering handle is attached to the handle shaft 1, whereby the steering torque applied to the handle shaft 1 is transmitted to the pinion shaft 2 via the torsion bar 8, causing the pinion 3 to rotate and the rack shaft 4 to slide. Steering is performed by

On the other hand, a pinion G is attached to the rotating shaft of the electric motor 50, and is coupled to the pinion shaft 2 via a bevel gear 7, so that torque is transmitted.

Therefore, when the electric motor 5 generates torque, this is applied to the pinion shaft 2, and as a result, auxiliary steering force (power assist) is obtained.

The magnetic drums 9 and 10 are drums whose peripheral portions are magnetized at a predetermined pitch, and are attached to the lower end of the handle shaft 1 and the upper end of the pinion shaft 2, respectively. Therefore, when the handle shaft 1 is rotated, the torsion bar 8 is twisted due to the torque transmitted from the handle shaft 1 to the pinion shaft 2 as it rotates together with the handle shaft 1, so that the magnetic drum 9 and the torsion bar 8 are twisted. Displacement appears at the inner rotational position of 10, and torque can be detected by the stiffness.

A magnetic resistance element 1 is combined with these magnetic drums 9 and 10 to constitute a non-contact torque sensor as a whole.
1 indicates a control circuit element 13 and a heat sink 15 on a circuit board 12;
It is integrated with a control circuit unit U consisting of the above power FET 14, a connector 17, etc., and is made into a unit. Simply attaching this control circuit unit U to a predetermined location of the sensor holding part (sensor housing) 20, A predetermined positional relationship can be obtained with respect to the magnetic drums 9 and 10.

Sensor holding part 20. The motor holding part 21 and the rack holding part m22 are made of aluminum die-casting or the like, and hold the handle shaft 1 and the binion shaft 2 with bearings 23 to 26, and also serve as mounting members for the control circuit unit U and the motor 5, and also serve as attachment members for the control circuit unit U and the motor 5. 3 and the rack shaft 4, and also functions to unitize the whole unit.

In FIG. 2, a vehicle speed signal V representing the speed of the electric motor 5 including the control circuit unit U is input into the microcomputer 13A and calculated.
The logic circuit 13B processes the signal, switches the bridge-connected FETs 14A to 14D to perform chopper control of the electric motor 5, and controls the current based on the detection signal of the current sensor 13D to obtain a predetermined auxiliary steering force (torque). be able to do so.

At this time, the power from Batch II B is turned on and off by the car's key switch K, and the voltages of 5V and 15V stabilized by the power supply circuit 13C are supplied to the microcomputer 13A and logic circuit 13BK. There is. Further, power to the electric motor 5 is supplied through the contacts of the relay R, and in the event of an abnormality, the motor 5 is turned off by releasing the relay R.

Figure 3 shows the assist torque (assistant steering force) characteristics relative to the value detected by the torque sensor.

The vehicle speed is taken as a parameter, and the assist torque decreases as the vehicle speed increases.

Next, a more detailed explanation will be given with reference to FIGS. 4 to 6.

In this embodiment, as is clear from FIG.
A4, IBI-IB4, and two sets of bridge-connected magnetic resistance elements 2A1-2A4.2B1-2B4 provided corresponding to the other magnetic drum 10.

Therefore, the steering wheel is now operated, and the steering wheel axis I
Suppose that a torque of K is applied to the motor and the motor is rotated.

Then, the voltage eAl shown in FIG. 5 is applied from the bridge formed by one magnetoresistive element IAI to IA4 corresponding to the magnetic drum 9, and the other magnetoresistive element IB1 to IB
A voltage eR+ is generated from each of the four bridges.

Since these voltages eAl and ell are generated with a 90 phase difference, when the position of the rotation angle of the nozzle shaft 1 is set as the reference point O, the rotation from this reference point O The angle θ is θH= tan (e nle
Al).

Also, one magnetic resistance element 2 corresponding to the magnetic drum 10
A voltage eAt is generated from the bridge made up of A1 to 2A4, and a voltage eat is generated from the bridge made up of magnetoresistive elements 2B1 to 2B4. These voltages e
At' and eB also have a 90° phase difference, and the sensing position is rotated by the rotation angle θ from the reference point O. Therefore, the rotation angle θ here.

is θ1=tan'(e it /e At )
Find 6t.

On the other hand, since the handle shaft 1 and the pinion shaft 2 are connected by a torsion bar 8, when torque is transmitted between these shafts, the rotation angle between the magnetic drums 9 and 10 changes depending on the magnitude of this torque. The difference between appears as θ, and θ=θI−
It becomes 6.

Therefore, the torque τ can be detected from this rotation angle difference θ, and the torque can be determined by setting θ=K(θ, −θt). Here, K is a constant determined by the rigidity of the torsion bar 8, etc.

Therefore, the microcomputer 13A, in the interrupt processing shown in FIG.
+eAI IeB, is sampled and taken in, and the rotation angle θ1. θ, calculation of torque, discrimination between clockwise rotation and counterclockwise rotation based on the sign of torque, search for IML 3 map for torque, calculation of IMC using vehicle speed correction coefficient kv, and converting IMC commands into 8-bit digital data. It is output to the D/A converter 44 as data. At this time, the operational amplifiers 40 to 43 have voltages eAl to e! An amplifier is configured to take in the lt, and the microcomputer 13A internally A/D converts it and takes it in. On the other hand, the vehicle speed signal V is passed through an input filter F,
The data is taken into the microcomputer 13A and counted.

In this way, the signal processed by the microcomputer 13A as shown in FIG. 6, input to the D/A converter 44, and converted into an analog signal becomes a non-inverting input of the deviation amplifier 45, and on the other hand,
The current signal of the electric motor 5 detected by the current sensor 13D becomes an inverting input of a deviation amplifier 45, and the deviation outputs thereof become an input of a pulse width modulation signal generator (PWM) 46. The output of the PWM 46 is a right/left discrimination output signal r,
In order to take an AND with L, it passes through Punt circuits 47 and 48 and then becomes input to FETs 14A and 14D.

On the other hand, the FETs 14A and 14C are turned on and off by generating a 15V power in the power supply circuit 13C and supplying this through the drive FE749.50 so that the gate voltage is not insufficient. Note that the inverters 51 and 52 are for buffers.

Therefore, according to this embodiment, the control circuit unit U and the magnetoresistive element 11 are integrated into a unit, so there is no need for an external arrangement, the assembly is simple, and the noise is not picked up. The probability is low, and it is small and highly reliable.

Further, according to this embodiment, since the control circuit unit U does not come into contact with parts that are likely to become high temperature, such as the electric motor 5, there is no problem in temperature control. Since the control circuit unit U is directly attached to the sensor housing (sensor holding part 20) with good radiation, cooling fins etc. can be made smaller and can be omitted in some cases, making it easy to reduce the weight.

Further, according to this embodiment, most of the mechanical parts of the power steering device including the electric motor 5 are the sensor holding part 20, the electric motor holding part 21, and the rack holding part i22.
Because it is integrated, it is compact and can be easily installed in the engine room of an automobile, making it possible to achieve sufficient cost reductions.

In addition, according to the above embodiment, four torque sensors are used as torque sensors.
Since the set of bridge-connected magnetoresistive elements IA1 to IA2B4 is used, signal detection is reliable and highly reliable.

It goes without saying that the present invention is not limited to the sensor using the above-described magnetoresistive element and magnetic drum, and may be implemented with any torque sensor as long as torque detection can be performed in a non-contact manner.

〔Effect of the invention〕

According to the present invention, since the entire unit can be sufficiently integrated without reducing reliability, torque control can be ensured, and a compact torque control device can be easily provided in a low-contact manner. .

[Brief explanation of the drawing]

1fW1 is a partial sectional view showing an embodiment in which the torque control device according to the present invention is applied to an m#h power steering device, and FIG. 2 is a block diagram of the control circuit unit. (￥3
The figure is a control characteristic diagram, and Figure 4 is a circuit diagram of a 1-nit control circuit.
FIG. 5 is a waveform diagram for explaining the operation, and FIG. 6 is a flow chart for explaining the operation. 1...Handle shaft, 2...Binioff f
nJ, 3... Binion, 4... Rack shaft, 5... Electric motor, 6... Binion,
7...Umbrella t4tjf, 8...Torsion bar, 9, 10...Magnetic drum, 11...
... Magnetoresistive element, 12 ... Circuit board, 13
...Control circuit element, 14...Power F
ET%U...Control circuit unit. District 1, Figure 2, Figure 3, Figure 4, Figure 5.

Claims (1)

[Claims] 1. Detecting torque transmitted along a predetermined rotation axis;
A torque control device of a type that controls an auxiliary torque to be applied to the torque output side of the rotating shaft according to the detection result, which includes a non-contact type sensor means for detecting the torque, and a non-contact type sensor means for controlling the auxiliary torque. A torque control device, characterized in that the electronic control circuit is integrally formed with the electronic control circuit, and is attached to an identification member that holds the rotation shaft. 2. In claim 1, the non-contact sensor means includes first and second magnetic drums respectively attached to the torque input side and the torque output side of the rotating shaft;
and first and second magnetic detection elements that magnetically detect the rotational angular position of the second magnetic drum as the sine and cosine values of a signal that changes in a sine wave pattern, the sine and cosine values of the signal being The rotation angle of the first and second magnetic drums is calculated based on the arctangent value of the ratio of , and the torque is detected as the difference between the rotation angles of the first and second magnetic drums. A torque control device featuring: 3. The torque control device according to claim 1, wherein the rotating shaft is a steering wheel shaft of an automobile, and the auxiliary torque acts as an auxiliary steering force. 4. In claim 3, the automobile has a rack-and-pinion steering system, and the auxiliary steering force for the pinion of the steering system has a rotation axis substantially parallel to the sliding direction of the rack. A torque control device characterized in that the torque is transmitted from an electric motor via a bevel gear.