JPS63240474A - Abnormally detecting device for car speed detector - Google Patents

Abstract

PURPOSE:To decide the first detector to be abnormal when the second detector detects a car speed to be in a preset value or more with a car speed, detected by the first car speed detector, less than the preset value, by providing the first car speed detector corresponding to the car speed and the second detector detecting the car speed to increase to the preset value or more. CONSTITUTION:A control means 48 connects the first car speed detector 49a, second car speed detector 49b and a lateral acceleration detector 50. The second car speed detector 49b, which serves as the switch conducted when a car speed increases to a preset value or more, is connected to an abnormality diagnostic circuit 67. This abnormality diagnostic circuit 67 inputs a signal corresponding to a car speed V from a pulse converter circuit 51. When the second car speed detector 49b is conducted and when the detected car speed V by the detector 49a is less than the preset value, the abnormality diagnostic circuit 67 decides the first car speed detector 49a to be in trouble, and the circuit 67 inputs its signal to a fail safe circuit 64 cutting off a transistor 65.

Description

[Detailed description of the invention] A0 Purpose of invention (11 industrial application fields The present invention relates to an abnormality detection device for a vehicle speed detector.

(2) Prior Art Conventionally, a vehicle speed detector is used, for example, in a vehicle speed-responsive power steering device to change the steering force in accordance with the vehicle speed.

(3) Problems to be Solved by the Invention Incidentally, in the above vehicle speed responsive power steering device, the steering force becomes heavier as the vehicle speed detected by the vehicle speed detector increases. If the system malfunctions and no longer outputs a signal, it will determine that the vehicle is stopped even though it is moving, and the steering force will be reduced. Therefore, when the vehicle speed detector fails, it is necessary to forcibly increase the steering force, but in this case, it is desirable to be able to detect that the vehicle speed detector is malfunctioning with a simple configuration.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a vehicle speed detector abnormality detection device that can easily detect abnormalities in the vehicle speed detector.

B1 Structure of the Invention (Means for Solving Problem 11) The device of the present invention includes a first vehicle speed detector that outputs a signal corresponding to the vehicle speed; a first vehicle speed detector that outputs a signal when the vehicle speed exceeds a set value. Two vehicle speed detectors: When both vehicle speed detectors are connected and the second vehicle speed detector detects that the vehicle speed is equal to or higher than the set value, the detected value of the first vehicle speed detector is less than the set value. and an abnormality diagnosis means for determining an abnormality depending on the condition.

(2) Effect According to the above configuration, when the second vehicle speed detector detects that the vehicle speed is equal to or higher than the set vehicle speed, if the detected value by the first vehicle speed detector is less than the set vehicle speed, the first vehicle speed is detected. 1
It is determined that the vehicle speed detector is abnormal, and the abnormality of the vehicle speed detector can be detected with a simple configuration.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, a power cylinder 2' is constructed in the middle of a rack rod 1 connected to a pair of left and right steering wheels (not shown). The inside of the power cylinder 2 is divided into a pair of left and right hydraulic chambers 4 and 5 by a piston 3 integrally provided on the rack rod 1.

A pinion 7 is engaged with a rack 6 provided on the rack rod 1, and a steering shaft 10 connected to a steering handle 9 is connected to a pinion shaft 8 provided with the pinion 7.

The pinion 7 is supported by a pinion holder 11 whose rotation center is eccentric to the rotation center of the pinion 7, and the rotation of the pinion 7 accompanying the rotation of the steering shaft 10 causes the rack rod 1 to rotate.
When the load increases, a reaction force acting on the pinion 7 to move the rack rod 1 in the axial direction acts on the pinion 7, and the pinion holder 11 rotates accordingly.

A switching valve 12 is interlocked and connected to the pinion holder 11 in order to switch the switching position according to the rotational movement of the steering shaft 10. This switching valve 12 has a spool valve body 14 in a valve surface 13.
A valve body 14 is connected to the pinion holder 11 via a pinion 15 at a position offset from the center of rotation.

The valve surface 13 includes a boat 17 communicating with one hydraulic chamber 4 of the power cylinder 2 via an oil passage 16, and a boat 19 communicating with the other hydraulic chamber 5 of the power cylinder 2 via an oil passage 18. A refueling boat 22 connected to the hydraulic pressure source 20 via an oil supply path 21 and an oil drain port 25 connected to the oil tank 23 via an oil drain path 24 are provided. Moreover, the spool valve body 14 is located at a position where the refueling boat 22 is communicated with one boat 19 and where the oil drain boat 25 is communicated with the other boat 17, and where the refueling boat 22 is communicated with the other boat 17 and the oil drain boat 25 is connected with the other boat 17. It is possible to switch between the position where it communicates with one boat 19 and the position where it communicates with one boat 19.

A plurality of, for example two, hydraulic reaction chambers 26 are provided in the valve face 13 around the spool valve body 14 . These hydraulic reaction chambers 26 are defined between a pair of plungers 27 and 28 that are movable in a direction parallel to the spool valve body 14 and are opposed to each other. A spring 29 is housed therein which biases 27 and 28 away from each other.

Moreover, both plungers 27 and 28 are engaged with the spool valve body 14, and the hydraulic pressure supplied to the hydraulic reaction chamber 26 is
The spool valve body 14 is urged toward the neutral position.

The hydraulic reaction chamber 26 and the oil supply path 21 are connected with a variable throttle valve 3 in the middle.
They are connected by a connecting oil passage 31 having a diameter of 0. The variable throttle valve 30 has a valve face 3 having an inlet port 32 and an outlet port 33.
A spool valve body 35 is slid into the inside of the valve face 34, and an oil tank 2 is provided between one end of the spool valve body 35 and one end wall of the valve face 34.
A sliding spring chamber 36 communicating with the spool valve body 35 is defined.
A cavity 38 defined between the other end and the other end wall of the valve face 34
communicates with the spring chamber 36 via a communication passage 37 formed in the spool valve body 35.

An annular groove 39 is provided on the outer surface of the spool valve body 35 for communicating between the inlet boat 32 and the outlet boat 33. The variable diaphragm 40 is constituted by the notch portion and the notch portion.

The spool valve body 3 is moved in a direction that increases the opening degree of the variable throttle 40.
5 (a spring 41 is housed in the spring chamber 36).

Also, the spool valve body 35 is driven in a direction that reduces the opening degree of the variable throttle valve 40 against the spring force of the spring 41 (a solenoid driving means 42 is connected to the variable throttle valve 30).

The solenoid driving means 42 includes a solenoid 44 in a housing 43 attached to the valve surface 34, and drives the spool valve body 35 toward the closing side of the variable throttle 40 in accordance with the excitation of the solenoid 44 (the movable core 45 moves forward). and a spring 46 that biases the movable core 45 in the backward direction.The movable core 45 is formed into a rod shape, and its tip movably penetrates the valve surface 34 and is inserted into the cavity 38. Furthermore, the amount of advance of the movable core 45 is proportional to the excitation current value of the solenoid 44, and therefore the opening degree of the variable throttle 40 is also inversely proportional to the excitation current value of the solenoid 44. and becomes small.

The hydraulic reaction chamber 26 is connected to the oil tank 23 via a fixed throttle 47.
will be communicated to. Therefore, the oil pressure in the hydraulic reaction chamber 26 is determined by the balance between the amount of oil supplied via the variable throttle 40 and the amount of oil discharged via the fixed throttle 47. Here, when the opening area of the variable throttle 40 is Sv, the opening area of the fixed throttle 47 is SF, and the oil pressure of the oil supply path 21 is P, the oil pressure P' of the hydraulic reaction chamber 26 is expressed as follows.

Sy"+Sv" Therefore, as the opening area of the variable throttle 40 becomes larger, the hydraulic pressure P' of the hydraulic reaction chamber 26 becomes larger.

In FIG. 2, the excitation current of the solenoid 44 in the solenoid drive means 42 is controlled by the control means 48, and the control means 4 detects the detection of the first vehicle speed detector 49a and the lateral acceleration detector 50 connected thereto. The excitation of the solenoid 44 is controlled according to the value. First vehicle speed detector 4
Reference numeral 9a obtains the vehicle speed as a pulse signal by detecting, for example, a magnet rotating together with a speedometer cable using a reed switch located at a fixed position.

Further, the lateral acceleration detector 50 detects the lateral acceleration of the vehicle, and may be of a potentiometer type consisting of a variable resistor and a pendulum, for example.

The control means 48 includes a pulse conversion circuit 51 that converts the signal from the first vehicle speed detector 49a into a voltage V proportional to the vehicle speed;
An inversion circuit 52 that inverts the voltage V, a voltage conversion circuit 53 that converts the output of the lateral acceleration detector 50 into a voltage, an absolute value circuit 54 that converts the output voltage of the voltage conversion circuit 53 into an absolute value, and a pulse conversion circuit 51 A multiplication circuit 55 that multiplies the output V of the output V and the output IG1 of the absolute value circuit 54, and a multiplication circuit 55 that inputs the output of the inversion circuit 52 as a non-inverting input.
a subtraction circuit 56 that performs subtraction processing by inputting the output of the subtraction circuit 56 as an inverted input, a drive circuit 57 that controls the solenoid 44 based on the output of the subtraction circuit 56, and a failsafe circuit 6.
4 and an abnormality diagnosis means 67, the solenoid 44 includes:
It is connected to a transistor 58 whose on/off is controlled by a drive circuit 57 and is grounded via a resistor 60 , and the drive circuit 57 is connected in parallel to the resistor 60 . Further, the positive terminal of the battery 59 is connected to the transistor 58 through a series circuit consisting of a transistor 65 and a resistor 66, and the transistor 65 is turned on and off by a fail-safe circuit 64.

Moreover, both ends of a resistor 66 are connected to the fail-safe circuit 64, and the current flowing through the resistor 66, that is, the excitation current of the solenoid 44, is detected by the fail-safe circuit 64.

A second vehicle speed detector 49b is connected to the control means 48. This second vehicle speed detector 49b is a switch that becomes conductive when the vehicle speed becomes equal to or higher than a set vehicle speed, for example, 40 km/h, and is connected to the abnormality diagnosis circuit 67. Further, a signal corresponding to the vehicle speed V is input from the pulse conversion circuit 51 to the abnormality diagnosis circuit 67, and when the second vehicle speed detector 49b is conductive, the vehicle speed detected by the first vehicle speed detector 49a is the set value. When the vehicle speed is lower than the vehicle speed, the abnormality diagnosis circuit 67 assumes that the first vehicle speed detector 49a has failed and inputs a signal indicating that the vehicle speed detector has failed to the failsafe circuit 64. On the other hand, the fail-safe circuit 64 includes the abnormality diagnosis circuit 6
Transistor 6 in response to the failure signal being input from 7.
Block out 5.

The fail-safe circuit 64 also includes a pulse conversion circuit 51.
A signal corresponding to the vehicle speed V is inputted from the vehicle speed V, and an excitation current is set in advance in the fail-safe circuit 64 according to the vehicle speed V, as shown by diagonal lines in FIG. Moreover, the fail-safe circuit 64 also has a function of cutting off the transistor 65 when the excitation current detected across the resistor 66 exceeds the set current.

According to the control means 48, the excitation current of the solenoid 44 is controlled as shown by the solid line in FIG. In other words, vehicle speed and excitation current are inversely proportional, and the proportionality constant is G for lateral acceleration. , G+ +, Gy * Gs. Further, as shown in FIG. 4, as the amount of excitation current of the solenoid 44 becomes smaller, the opening degree of the variable diaphragm 40 becomes larger.

The hydraulic pressure source 20 includes a hydraulic pump 61 that is linked to an engine (not shown), a flow M8 regulating valve 62 for maintaining a constant amount of hydraulic oil discharged into the oil supply passage 21, and a hydraulic pressure regulator 62 for maintaining a constant amount of hydraulic oil discharged into the oil supply passage 21. and a relief valve 63 for preventing the air from rising.

Next, the operation of this embodiment will be explained. The excitation current of the solenoid 44 in the solenoid drive means 42 is controlled to be inversely proportional to the vehicle speed while increasing the proportionality constant as the lateral acceleration increases. The opening increases proportionally as the vehicle speed increases, and the degree of increase or decrease changes depending on the magnitude of the lateral acceleration.

That is, as shown in FIG. 5, when the vehicle speed is zero CV, the variable throttle 40 is closed and the steering force is constant with respect to the road load, but when the vehicle speed is low ■β, medium speed Vm, and high speed V
As the speed increases to h, the steering force also increases, and as the lateral acceleration increases to Go, G+, Gt, and G, it further increases.

However, in driving modes such as in urban areas where driving is often done at relatively low speeds, the opening degree of the variable throttle 40 is made small, the hydraulic pressure in the hydraulic reaction chamber 2b is made low, and the steering force is made small to provide light driving. During 6-hour driving, you can get a comfortable steering feel. On highways and mountain roads where high-speed driving is common, the steering force increases linearly with the steering angle, and when driving on winding roads, etc., where quick steering operation is required. In situations where the lateral acceleration is high, the steering force can be increased progressively with respect to the steering angle, and sufficient feedback can be given to the driver.

Further, when the excitation current of the solenoid 44 exceeds the set current indicated by diagonal lines in FIG. (When the opening is reached, the transistor 65 is cut off by the fail-safe circuit 64, and the opening of the variable diaphragm 40 becomes fully open.

Therefore, the hydraulic pressure in the hydraulic reaction chamber 26 becomes high (and the steering force becomes heavy, so the steering force does not become light during high-speed driving.The set current of the solenoid 44 is set to decrease as the vehicle speed increases. This improves abnormality detection accuracy, especially at high speeds.

Furthermore, even when the abnormality diagnosis circuit 67 detects that the first vehicle speed detector 49a has failed, the failsafe circuit 64 shuts off the transistor 65 and demagnetizes the solenoid 44, so that the steering force is not reduced. .

As another embodiment of the present invention, a fixed throttle is provided between the oil supply passage 21 and the hydraulic reaction chamber 26, and a variable throttle is provided between the oil supply passage 21 and the hydraulic reaction chamber 26.
and the oil tank 23 to control the amount of oil discharged from the hydraulic chamber 26. In this case, a variable valve configured so that the opening degree of the throttle becomes the minimum when no solenoid current is flowing. Aperture is applied.

Effects of the C0 Invention As described above, the present invention device includes: a first vehicle speed detector that outputs a signal corresponding to the vehicle speed; a second vehicle speed detector that outputs a signal when the vehicle speed exceeds a set value; When both vehicle speed detectors are connected and the second vehicle speed detector detects that the vehicle speed is equal to or higher than the set value, an abnormality occurs when the detected value of the first vehicle speed detector is less than the set value. Since the present invention includes an abnormality diagnosing means for determining that the first vehicle speed detector has failed, it is possible to detect that the first vehicle speed detector has failed with an extremely simple configuration.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is an overall hydraulic circuit diagram in a state where the vehicle is traveling straight at low speed, Fig. 2 is a block circuit diagram showing the configuration of the control means, and Fig. 3 is a diagram showing the vehicle speed and lateral acceleration. FIG. 4 is a graph showing the relationship between the solenoid exciting current and the aperture opening, and FIG. 5 is a graph showing the relationship between the steering force and the road load. 49a... First vehicle speed detector, 49b... Second vehicle speed detector, 67... Abnormality diagnosis circuit

Claims (1)

[Claims] a first vehicle speed detector that outputs a signal corresponding to the vehicle speed; a second vehicle speed detector that outputs a signal when the vehicle speed exceeds a set value; both vehicle speed detectors are connected, and the second vehicle speed detector and an abnormality diagnosis means for determining an abnormality when the detected value of the first vehicle speed detector is less than the set value when it is detected that the vehicle speed is equal to or higher than the set value. Abnormality detection device for vehicle speed detector.