JPH0774023B2 - Damping force control device for steering damper of motorcycle - Google Patents

Description

TECHNICAL FIELD The present invention relates to improving the function of a steering damper provided in a steering wheel of a two-wheeled vehicle.

(Prior Art) As a steering damper for damping the vibration transmitted from the front wheels to the steering wheel, for example, a steering damper as shown in FIG. 6 is known. This is defined by oil-free chambers 22 and 23 on both sides defined by a piston 21 that is slidable inside the cylinder 20. The oil chambers 22 and 23 are pressure control valves via check valves 24 and 25, respectively. It communicates with 1. Further, the pressure control valve 1 communicates with an accumulator 27 that absorbs the volume change, and the accumulator 27
Communicates directly with oil chambers 22 and 23 via check valves 28 and 29. The pressure control valve 1 is configured to change the valve opening pressure by a current supplied from an external power source (not shown).

In this steering damper, the piston 21 is the cylinder
When the inside of 20 is displaced to the oil chamber 22 side, the hydraulic oil in the oil chamber 22 passes through the check valve 24, pushes the pressure control valve 1 open, and opens the check valve 29.
To the oil chamber 23 and the piston 21 is displaced toward the oil chamber 23 side, the working oil in the oil chamber 23 flows into the oil chamber 22 through the check valve 25, the pressure control valve 1 and the check valve 28. In either case, the damping force is generated by the resistance of the hydraulic oil when passing through the pressure control valve 1. By controlling the current supplied to the pressure control valve 1 in cooperation with a vehicle speed sensor and a steering wheel angle sensor (not shown), a damping force corresponding to the vehicle speed and the steering wheel angle can be obtained.

Further, by further accumulating between the oil chamber 22 and the check valve 24 and between the oil chamber 23 and the check valve 25, it is possible to absorb a minute vibration that does not result in opening the pressure control valve 1. There is also proposed a steering damper (Japanese Patent Laid-Open No. 60-18630).

(Problems to be solved by the invention) By the way, when the direction of the steering wheel and the traveling direction of the two-wheeled vehicle are different, such as when landing from a jump or wheelie state or after passing through a recess, the ground contact point of the front wheel is on the steering axis. Since the front wheels are not landing, the steering resistance is shaken in cooperation with the backward running resistance that acts on the grounding point at the same time as the landing of the front wheels. However, if the damping force of the pressure control valve 1 is set to be large in order to alleviate this with the steering damper, the damping force during normal traveling also becomes large, and handling becomes extremely heavy overall. On the other hand, if importance is attached to light handling during normal driving, the kickback phenomenon cannot be suppressed by the steering damper, and the steering wheel swing must be suppressed by the strength of the arm. That is, it is difficult for the steering damper to achieve both light handling and suppression of the kickback phenomenon.

In view of the above problems, it is an object of the present invention to provide a steering damper control device capable of temporarily increasing the damping force only for a kickback phenomenon.

(Means for Solving the Problems) The present invention controls the energization to a Solenoid type pressure control valve interposed in an oil passage of a steering damper provided in a steering wheel of a two-wheeled vehicle to reduce a damping force generated by the control valve. A damping force control device for a steering damper to be changed is provided with a front wheel load detecting means for a two-wheeled vehicle, and a control circuit for controlling energization to the control valve so as to increase the damping force based on the decrease in the detected front wheel load. .

(Operation) Before the kickback phenomenon, the load applied to the front wheels decreases compared to normal running, so the detection means detects this decrease in the front wheel load, and the control circuit then energizes the solenoid of the damping valve based on this. Control to increase damping force.

(Embodiment) FIGS. 1 to 5 show an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a pressure control valve provided in an oil passage in the steering damper, and a control current I supplied through a control unit 2 which is a control circuit controls a valve opening pressure and an oil passage after opening the valve. Change resistance. A signal from a pressure sensor 3 provided for detecting the load on the front wheels and a signal from a steering wheel angle sensor 4 provided on the steering wheel are input to the control unit 2. The pressure sensor 3 is provided inside the front fork supporting the front wheel, and detects the pressure P of the air chamber rising due to the contraction of the front fork and outputs a signal to the control unit 2. Further, the steering wheel angle sensor 4 detects a steering wheel rotation angle φ from the longitudinal line of the vehicle body and outputs a signal to the control unit 2.

The pressure P from the pressure sensor 3 is applied to the control unit 2.
Pressure P (1G) preset for the signal input of
A differential amplifier 5 that outputs a difference ΔP from The pressure P (1G) is the air chamber pressure inside the front fork at the equilibrium position during normal traveling. Also, this difference ΔP
Is provided with a comparator 6 for comparing ΔP _max set separately.
ΔP _max is the difference between the pressure P ₀ inside the front fork and the set value P (1G) when the front wheels are floating in the air, and ΔP is ΔP _max
The comparator 6 conducts the relay 7 and supplies a constant current I ₀ from the power source 8 to the adding circuit 9 only when the value is equal to or greater than. The control unit 2 also comprises a function conversion circuit 10 for converting the pressure difference ΔP output from the differential amplifier 5 into the corresponding proportional constant K as shown in the figure. Further, a differentiation circuit 11 for obtaining the rotation speed dφ / dt of the steering wheel from the rotation angle φ of the steering wheel detected by the steering wheel angle sensor 4, and this rotation speed d
and a multiplication circuit 12 for multiplying φ / dt by the proportional constant K. Signal current output from multiplication circuit 12 Is input to the adder circuit 9, and the adder circuit 9 outputs the signal current The current I, which is the sum of the constant current I ₀ and
Output as control current of.

Next, the operation will be described.

The load on the front wheels, which is applied to the front wheels when traveling stably on a flat road, is higher than the load on the front wheels when braking or when passing through a convex portion, and is less than when loading through a concave portion. Furthermore, when the front wheels are lifted off the ground, such as when jumping or running on a wheelie, the front wheel load becomes zero. The expansion / contraction position of the front fork supporting the front wheel changes depending on the front wheel load, and the pressure P of the air chamber above the hydraulic oil chamber enclosed in the front fork also changes correspondingly. In this control system, the control unit 2 controls the pressure control valve 1 as follows based on the hydraulic oil pressure P detected by the pressure sensor 3 and the steering wheel angle φ detected by the steering wheel angle sensor 4.

When the detected pressure P of the pressure sensor 3 is equal to or higher than the hydraulic oil pressure P (1G) in the load state of 1G, the output ΔP ≦ 0 of the differential amplifier 5 is satisfied, and thus the function conversion circuit 10 converts the pressure. The proportional constant K is 0, and the comparator 6 also has a relay 7
It does not lead to switching. Therefore, the control current I output from the adder circuit 9 is set to 0 regardless of the rotation speed dφ / dt of the steering wheel as shown in FIG. That is, the pressure control valve 1 of the steering damper is held in the fully open state,
As shown in the figure, the damping force is minimally generated as the steering wheel speed dφ / dt increases, and is minimized, so the steering wheel operation is light and the driver is not tired.

Next, when the front wheel passes through the concave portion, the front fork extends and the pressure P decreases, and the output ΔP> 0 of the differential amplifier 5 of the control unit 2 becomes. This allows the function conversion circuit
10 converts ΔP into a corresponding proportional constant K and inputs the signal to the multiplication circuit 12. On the other hand, the handle rotation speed dφ / dt obtained by differentiating the handle angle φ detected by the handle angle sensor 4 by the differentiating circuit 11 is input to the multiplying circuit 12, and the multiplying circuit 12 is the product of these.

To the adder circuit 9 as a signal current. At this time, if the front wheels are not floating in the air, ΔP <ΔP _max .
The comparator 6 does not switch the relay 7 and is disconnected from the power supply 8 and the adding circuit 9. Therefore, the adder circuit 9 receives the signal current input from the multiplier circuit 12. Is output as it is to the pressure control valve 1 as the control current I.
Therefore, the control current I changes in proportion to the proportional constant K and the handle rotation speed dφ / dt as shown by W _{1 to} W ₃ in FIG. 2, and the damping force generated by the pressure control valve 1 also appears in FIG. So it changes correspondingly. Therefore, the steering damper generates a greater damping force as the front wheel load is smaller, and prevents the steering wheel from swinging after passing through the recess.

Further, in the state where the front wheels are completely lifted up in the air such as jumping or wheelie running, the pressure P detected by the pressure sensor 3 becomes the minimum, and the output ΔP of the differential amplifier 5 becomes equal to the set value ΔP _max . As a result, a signal current is output from the comparator 6, the relay 7 is rendered conductive, and the power source 8 outputs a constant current I ₀ to the adding circuit 9. Therefore, the control current I output from the adding circuit 9 is the signal current input from the multiplying circuit 12. This current I ₀ is added to. Therefore, this control current I is the steering wheel speed d as shown by W ₄ in FIG.
It does not become 0 even when φ / dt = 0, and increases with the handle rotation speed dφ / dt starting from I ₀ . as a result,
The damping force generated by the pressure control valve 1 is as shown by W ₄ in FIG. 3, and the initial value F ₀ stably holds the steering wheel in the air, and the steering wheel speed dφ for kickback when the front wheels land. The damping force, which increases with / dt, strongly damps the vibration of the steering wheel. Therefore, the handle is not taken off at the time of landing, and the arm that supports the handle does not receive a large force. Further, after landing, the pressure P detected by the pressure sensor 3 rises due to the contraction of the front fork, and the control current I ₀ output by the control unit 2 decreases, so the damping force of the pressure control valve 1 also decreases at the same time and the state of W ₀ Return to.
Therefore, the handle operation after landing can be performed with a light force.

The stroke position of the front fork may be detected instead of using the pressure sensor 3 as the front wheel load detecting means. In that case, the stroke sensor that detects the stroke position has a structure in which a plurality of reed switches provided on one of the cylinder and piston rod of the front fork damper are sequentially switched by the magnet attached to the other along with the stroke, or on the cylinder side. A primary and a secondary coil are provided, and a so-called differential transformer is used in which the output voltage of the secondary coil changes according to the displacement when the magnetic body provided on the piston side is displaced relative to these coils. . The setting value of the differential amplifier 5 of the control unit 2 is the stroke position X under the load condition of 1G.
(1G), the function conversion circuit 10 is configured so that the proportional constant K is determined with respect to the detected stroke position X and ΔX. Similarly, the set value of the comparator 6 is also set to ΔX _max , which is the difference between the stroke position X and X (1G) when the front wheel is floating in the air.

Further, the present invention can be implemented with a configuration as shown in FIG. 4 which does not use the steering wheel angle sensor 4. In this case, since the control current I is changed using only the pressure P detected by the pressure sensor 3 as a parameter, the rate of increase of the damping force with respect to the steering wheel rotation speed dφ / dt during normal traveling and when the front wheels are lifted is as shown in FIG. However, the control unit 2 has a differential amplifier 5 and a function conversion circuit as shown in FIG.
It has a simple structure with only 10 and does not require the steering wheel angle sensor 4, so that it can be implemented at low cost.

As described above, the present invention includes the means for detecting the front wheel load of the two-wheeled vehicle and the control circuit for controlling the energization of the pressure control valve of the steering damper based on the front wheel load detected by the detecting means. Therefore, when the front wheels float in the air due to a jump, a wheelie run, or passage through a recess, the damping force of the steering damper can be temporarily increased in preparation for a kickback phenomenon that occurs when the front wheels come into contact with the ground. That is,
Since it is possible to prevent the steering wheel from swinging due to the kickback phenomenon without affecting the damping force during normal traveling, it is possible to obtain the effect of greatly improving the steering stability of the motorcycle.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
FIG. 4 is a graph showing the characteristics of the control voltage in the same example, FIG. 3 is a graph showing the same damping force characteristics, FIG. 4 is a block diagram showing the structure of another embodiment, and FIG. 5 is the same damping force characteristics. It is a graph. Further, FIG. 6 is a circuit diagram of a control system of a steering damper showing a conventional example. 1 ... Pressure control valve, 2 ... Control unit, 3 ...
… Pressure sensor.

Claims (1)

[Claims] 1. A damping force control device for a steering damper, which controls energization of a solenoid type pressure control valve provided in an oil passage of a steering damper provided in a steering wheel of a motorcycle to change a damping force generated by the control valve. In a steering damper of a two-wheeled vehicle, a front wheel load detecting means for a two-wheeled vehicle is provided, and a control circuit for controlling energization to the control valve is provided so as to increase a damping force based on a decrease in the detected front wheel load. Damping force control device.