JPS62255277A - Steering force control current arithmetic unit - Google Patents

Abstract

PURPOSE:To make the extent of memory capacity smaller, by interpolating and operating current values in both upper and lower limits of two car speeds at an inflection point on the basis of a car speed and a steering angle, and furthermore interpolating and operating an output current value from these two current values. CONSTITUTION:In a read-only memory 83, a three-dimensional map, programming desired current valves ia-id at discrete inflection points (a)-(d) which define a current characteristic as setting an X-axis to a car speed V, a Y-axis to a steering angle theta and a Z-axis to a current value (i), is being stored. And, the car speed V and the steering angle theta detected by a car speed sensor 89 and a steering angle sensor 88 are read in, whereby a current value iA at time of the steering angle theta in the lower limit value VL of the car speed is interpolated and operated from the map, and successively a current value iB at time of the steering angle theta in the upper limit value VH of the car speed is interpolated and operated from data of the map. In succession, an output current value iO at time of the car speed V in the steering angle theta is interpolated and operated on the basis of the said current values iA and iB. Therefore, it will do that only the desired current value at the inflection point is merely stored.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a steering force control current calculation device that calculates a current value for steering force control of a power steering device.

<Prior art> A steering force control device that controls the steering force of a power steering device according to vehicle speed and steering angle uses a solenoid valve that is controlled by a current value that corresponds to vehicle speed and steering angle. The valve controls the pressure or flow rate of the hydraulic circuit of the power steering device in accordance with the vehicle speed and steering angle, thereby controlling the steering force in accordance with the vehicle speed and steering angle.

In this type of steering force control device, in order to supply a current value to the solenoid valve according to the vehicle speed and steering angle, current characteristics are programmed in the memory in the form of a map. The target current value is read out. In other words, the vehicle speed range in which the steering force should be controlled is divided into multiple regions, and a large number of maps are stored in memory in which target values corresponding to the steering angle are programmed for each of these vehicle speeds. A map is selected, and a target current value corresponding to the steering angle is searched from this map and output.

<Problems to be solved by the invention> However, in the map search method described above,
Since it is necessary to store a large amount of continuous data as the target current value in the memory, there is a problem that the memory capacity becomes large.

<Means for Solving the Problems> The present invention has been made to solve the above-mentioned problems of the conventional art, and its configuration is based on the following: A storage device that stores a map in which a target current value is programmed, a vehicle speed sensor that detects vehicle speed ■, a steering angle sensor that detects steering angle θ, and vehicle speed V and steering detected by these vehicle speed sensors and steering angle sensors. The current value at the steering angle θ (or vehicle speed ■) at the lower limit VL (θL) and upper limit VH (θH) of the vehicle speed ■ (or steering angle θ) at the inflection point is calculated based on the angle θ. 1 calculation means;
From the two current values at the steering angle θ (or vehicle speed V) calculated by the first calculation means, the vehicle speed V (or the steering angle θ
), and a second calculating means for calculating the output current value at the time of

<Embodiment> Hereinafter, an embodiment of the present invention will be described based on the drawings for an example in which steering force is controlled by a hydraulic reaction force mechanism.

8 and 9 show a power steering device equipped with a hydraulic reaction force mechanism, 11 is a housing main body forming the main body of the power steering device, and 12 is a valve housing fixed to the housing main body 11. A pinion shaft (output shaft) 21 is rotatably supported in the housing body 11 and the valve housing 12 via a pair of bearings 13 and 14, and a pinion shaft 21 is slidable in a direction crossing the pinion shaft 21. The rank teeth 22a of the possible rank shafts 22 are in mesh. This rack shaft 22 is connected to a piston of a power cylinder 15 (FIG. 7), and both ends thereof are connected to steering wheels via a required steering link mechanism.

A servo valve 30 is housed in the large circle of the valve housing 12. The servo valve 30 mainly includes a rotary valve member 31 formed integrally with an input shaft 23 as a steering shaft, and a sleeve valve member 32 fitted to the outer periphery of the rotary valve member 31 concentrically and relatively rotatably. It is used as a component. The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24 whose one end is connected to an input shaft 23 integral therewith. Further, although not shown, on the outer periphery of the rotary valve member 31, a plurality of land portions and groove portions extending in the axial direction are formed at equal intervals, and a communication path that communicates from the bottom of the groove to the inner peripheral portion. 37 are drilled.

The input shaft 23 is provided with a passage 39 that communicates the inner peripheral portion with the low pressure chamber 38 within the valve housing 12 . On the other hand, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the inner periphery of the sleeve valve member 32, and distribution holes 40° 41 are provided that open from each groove to the outer periphery of the sleeve valve member 32. ing. When the servo valve 30 is in the neutral state, the pressure fluid supplied from the supply port 35 flows equally into the grooves on both sides of the land portion, and flows out from the low pressure chamber 38 to the discharge boat 36 via the communication passage 37 and the passage 39. In this case, the power cylinder 15 is not activated because the redistribution boats 33 and 34 are at low and equal pressures. If the servo valve 30 deviates from the neutral state, pressure oil is supplied from the supply boat 35 to one distribution hole 40 or 41, and the other distribution hole 41 is supplied with pressure oil.
Alternatively, fluid discharged from the power cylinder 15 flows into the passage 40 and is discharged to the discharge port 36 via the communication passage 379 passage 39° and the low pressure chamber 38.

The reaction force mechanism is as follows. As shown in FIG. 9, a protrusion 50 that protrudes in the diametrical direction is formed at the end of the rotary valve member 31 on the binion shaft 21 side.
A protrusion 50 is attached to the pinion shaft 21 corresponding to the input shaft 2.
A fitting groove 51 is formed into which the fitting groove 51 is loosely fitted so as to be rotatable by several angles around the axis of the fitting.

Insertion holes 53 are formed in the nion shaft 21 on both sides of the protrusion 50, and a plunger 54 is slidably inserted into each of the insertion holes 53. This plunger 54 is projected forward by hydraulic pressure introduced into a reaction force chamber 55 formed at the rear thereof, and holds the protrusion 50 from both sides thereof, and its forward end is connected to a large diameter portion formed in the plunger 54. 54a. 57
58 is a passage, and 59 is an annular groove that communicates the passage 58 with the reaction force chamber 55.

In FIG. 7, 60 is a supply pump driven by an automobile engine, and 61 is a flow control valve that controls the flow rate Q of pressure oil discharged from the supply pump to a constant flow rate Q. The flow rate control valve 61 is operated according to the metering orifice 62 and the longitudinal pressure of the metering orifice 62, and controls the opening of the bypass passage 63 leading to the low pressure side so as to keep the longitudinal pressure constant. It is constituted by a bypass valve 64.

Reference numeral 65 denotes a flow divider that is connected to the high pressure side of the flow rate control valve 61. The spool hole 65a of this branch control valve 65 has a first control hole 68 communicating with the supply port 35 of the servo valve 30 via the passage 45, and a reaction force chamber 5.
A second control hole 69, which communicates with the introduction boat 57 through the passageway 46, is opened at a distance therebetween. In addition, a control spool 67 is slidably provided in the spool hole 65a, and is equipped with a control throttle 66 that divides the pressure oil at the constant flow rate Q into the first control large 68 and the second control hole 69 into constant flow rates QG and QR. The control spool 67 is fitted into the first control hole 68 and the second control hole 67 so as to maintain the front and rear pressure of the control throttle 66 constant.
The opening area of the control hole 69 is controlled. The reaction force chamber 55
The passage 46 communicates with the reservoir via an electromagnetic throttle valve 70.

The electromagnetic throttle valve 70 has a throttle area that varies linearly depending on the vehicle speed and the like.

With the above configuration, the pressure oil discharged from the supply pump 60 is controlled to a constant flow rate Q by the flow control valve 61, and the pressure oil at this constant flow rate Q is transferred to the servo valve 30 side and the reaction chamber 55 by the flow control valve 65. The pressure oil separated to the reaction force chamber 55 side is drained to the tank via the electromagnetic throttle valve 70. Therefore, the throttle area of the electromagnetic throttle valve 70 is changed according to the current value supplied to the solenoid of the electromagnetic throttle valve 70, and the pressure corresponding to the outflow resistance is adjusted to the reaction force chamber 5.
5, and the steering force is changed. Therefore, the steering force is controlled according to the current value supplied to the electromagnetic throttle valve 70.

Next, a control device that calculates an output current value to be supplied to the solenoid of the electromagnetic throttle valve 70 according to the vehicle speed and steering angle will be described.

In FIG. 1, 80 is an electronic control unit, and this electronic control unit 80 has a microprocessor 81, a writable memory (hereinafter simply referred to as RAM) 82, and a read-only memory (hereinafter simply referred to as ROM) 83 as its main components. , this microprocessor 81 has an interface 84
A solenoid drive circuit 85 is also connected to the solenoid drive circuit 85 to control the current applied to the solenoid of the electromagnetic throttle valve 70. Further, a steering angle sensor 88 is connected to the microprocessor 81 via an interface 86 and a phase determination circuit 87. The steering angle sensor 88 consists of a rotating plate fixed on the handle shaft and two photointerrupters that output a signal for each unit angle of the rotating plate.
The steering wheel steering angle θ is detected based on the signal from the photo ink club. Furthermore, a vehicle speed sensor 89 is connected to the microprocessor 81 via an interface 86 . This vehicle speed sensor 89 is composed of a rotating needle connected to the output shaft of the transmission, and is configured to detect the vehicle speed V based on the frequency of a pulse signal generated from this vehicle speed sensor 89.

On the other hand, the ROM 83 stores a three-dimensional map in which current characteristics with respect to vehicle speed (2) and steering angle (theta) are programmed. As shown in Fig. 2, this three-dimensional map is constructed by setting the X-axis to vehicle speed v, the y-axis to steering angle θ, and the Z-axis to current value i.
Target current values ia to id at discrete inflection points a% d that define current characteristics are programmed, and at the inflection point a, the lower limit value θ of the steering angle θ at the lower limit value v of the vehicle speed
Similarly, the target current value ia at the time of L is determined, and similarly, at the inflection point, the lower limit value of the vehicle speed is V, the target current value ib at the upper limit of the steering angle is 88, and at the inflection point C, the upper limit value of the vehicle speed is V. ,, the target current value ic at the lower limit value θL of the steering angle is the upper limit value V Hs of the vehicle speed at the inflection point d, and the target current value id when the upper limit value of the steering angle is 88
are determined respectively. These discrete inflection points a
Target current value 1a-ib by target current value i a ''-i d at z d.

1a-ic, 1b-td, and tc-id are connected with a straight line, and the current characteristics are saturated when the vehicle speed and steering angle are below the lower limit value V L + θL and above the lower limit values VH and θH. .

In other words, the above three-dimensional map is a first characteristic map (Fig. 3) in which the target current value for the steering angle θ at the lower limit value v of the vehicle speed is programmed, and a map for the steering angle θ at the upper limit value V of the vehicle speed. The second one with the target current value programmed.
It consists of the characteristic map (Figure 4).

Next, the control program will be explained based on FIG.

First, in step 100, the vehicle speed V and steering angle θ detected by the vehicle speed sensor 89 and the steering angle sensor 88 are determined by an interrupt signal every predetermined travel distance or unit time.
are read, and in steps 101 to 104, it is determined whether the read vehicle speed (2) and steering angle θ are a lower limit value v, which is smaller than θL, and whether or not they are larger than an upper limit value VH+θH. Vehicle speed■ and steering angle θ are both lower limit values■
If the target current value ia is smaller than θL, the target current value ia is read as the output current value to in step 105, and if the vehicle speed ■ is greater than the upper limit value V+ and the steering angle θ is smaller than the lower limit value θL, the output current value value 10
If the steering angle θ is larger than the upper limit value θH, the target current value 1b(id) is read as the output current value 10 in step 107.

However, if at least one of the vehicle speed V and the steering angle θ is between the lower limit value and the upper limit value, step 10
8, and in step 108, the current value iA at the steering angle 6 at the lower limit value v of the vehicle speed is calculated by interpolation from the data of the map I, and then in step 109, the current value iA at the upper limit value VH of the vehicle speed is calculated from the data of the map Steering angle 6
The current value 1B at the time is calculated by interpolation. Then step 11
0, the output current value 1 at steering angle θ and vehicle speed 7
0 is interpolated based on the current values i^ and iB, and this output current value 10 is output from step 111 and applied to the electromagnetic throttle valve 70 for controlling the steering force described above.

This interpolation calculation will be specifically explained by applying numerical values. - As an example, the lower limit of vehicle speed ■ is 3Qkm.
/h, upper limit value V is 80 km/h, lower limit value θL of steering angle θ is 45 deg, upper limit value θH is 180 deg,
When the target current value 1axid at the lower limit value and upper limit value of the steering angle θ with respect to the lower limit value and upper limit value of the vehicle speed ■ is programmed as shown in the table below, when the vehicle speed V is 50
kll/h, output current value to when steering angle θ is 9Qdeg
will be determined by interpolation calculation.

■ First, in step 108, the vehicle speed ■ is 30 km.
From the map I (Figure 3) in which the current value is programmed for the steering angle θ at the time of /h, the current value i at the steering angle 90 degrees is determined.
Find A. In this case, iA is located on a straight line connecting the current value IA when the steering angle is 45 degrees and the current value 0 when the steering angle is 180 degrees, and is determined by the following calculation formula.

Subsequently, in step 109, the vehicle speed ■ is 3Qk.
The current value 1B at a steering angle of 9Qdeg is determined from the map (Fig. 4) in which the current characteristics with respect to the steering angle θ at m/h are programmed. In this case, iB is located on a line connecting a current value of 0.3 A at a steering angle of 45 degrees and a current value of 0 at a steering angle of 180 degrees with a straight line, and is obtained from the following calculation formula in the same manner as above.

Furthermore, in step 110, the steering angle 9Qde
Vehicle speed at g hour: 30 km/h, 80 kra
Vehicle speed 50km/h from each current value i^+ 18 at /h
The output current value 10 at the time is determined by interpolation calculation. This can be diagrammed as shown in Figure 5. That is, the output current value 10 is as follows.

In the above embodiment, an example was described in which two inflection points were set for vehicle speed and steering angle, but when the current characteristics are defined by three or more inflection points for vehicle speed and/or steering angle. includes the detected vehicle speed,
Current values at two inflection points to be interpolated may be selected based on the steering angle.

Further, in the above embodiment, in order to obtain the output current value 10 when the vehicle speed is v and the steering angle θ, the current value 'Ar iB at the lower limit value v and the upper limit value V of the vehicle speed when the steering angle is 6 is used.
The output current value 10 at a vehicle speed of 1 o'clock was obtained from these current values IA + IB, but conversely, each current value at the lower limit value θL and upper limit value θH of the steering angle at a vehicle speed of 7 hours was first determined, and these An output current value of 10 at a steering angle of 6 o'clock can also be determined from the current value.

Furthermore, in the above-described embodiments, an example was described in which a solenoid valve for controlling reaction force is controlled, but it goes without saying that the present invention can be applied to any device in which steering force is controlled based on a current value.

<Effects of the Invention> As described above, the present invention defines the current characteristics with respect to vehicle speed and steering angle by target current values at discrete inflection points, and the vehicle speed V and steering angle θ detected by the sensor
Two vehicle speed values vL r at the inflection point based on
The configuration is such that the current value at steering angle 6 at VH is interpolated and then the output current value at vehicle speed 7 is interpolated from these two current values, so the memory stores discrete inflection points. Since it is only necessary to store a limited number of target current values, the memory capacity is small, and the optimum output current value can be calculated according to the vehicle speed and steering angle.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a block diagram showing the entire steering force control current calculation device, FIG. 2 is a three-dimensional map, and FIGS. A diagram showing current characteristics with respect to steering angle in a vehicle speed range, FIG. 5 is a diagram illustrating interpolation calculation, FIG. 6 is a diagram showing a flowchart, and FIG. 7 is a power steering device suitable for applying the present invention device. Fig. 8 is a sectional view of a power steering device equipped with a hydraulic reaction force mechanism, and Fig. 9 is a hydraulic system diagram showing a steering force control device.
w d... point of inflection.

Claims (1)

[Claims] (1) A map in which target current values at discrete inflection points that define current characteristics with respect to vehicle speed and steering angle are programmed for a steering force control current calculation device that calculates current values for steering force control of the power steering device. a storage device for storing the vehicle speed V, a vehicle speed sensor for detecting the vehicle speed V, a steering angle sensor for detecting the steering angle θ, and a vehicle speed V and the steering angle θ detected by the vehicle speed sensor and the steering angle sensor. Lower limit value V_L(θ
_L) and the steering angle θ at the upper limit value V_H (θ_H)
(or vehicle speed V).
a calculation means and a steering angle θ calculated by the first calculation means;
(or vehicle speed V); and second calculation means for calculating an output current value at vehicle speed V (or steering angle θ) from two current values at vehicle speed V (or vehicle speed V).