JPH02220911A - Caster trail control system - Google Patents

Abstract

PURPOSE:To increase straightforward traveling, steering, and braking performances by connecting a control valve, switching over caster trail larger or smaller according to the operation of a power steering system and a brake system, to a caster variable actuator, in the above system for automobile. CONSTITUTION:A caster trail control valve 10 is operated by a pressure difference generated in pipes 24 and 25 connected to an actuator 26 of a power steering system 2. On the other hand, the delivery pressure generated by a pump 20 of the power steering system 2 is applied to the chamber 5a of a caster variable actuator 4 through a pipe 30 and the caster trail control valve 10. Also, a pressure from the master cylinder 37 of a brake system 3 is applied to the chamber 5a. Accordingly, a caster trail L is so controlled that it becomes larger when a car travels in straightforward direction, smaller when it is steered, and larger when it is braked. Thus, braking, steering, and straightforward traveling performances can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement in a caster trail control system that automatically varies the caster trail of, for example, an automobile.

(Prior Art) In recent years, caster trail control systems for passenger cars and the like have been developed that vary caster trails in accordance with vehicle speed in order to improve running stability.

Conventionally, this type of caster trail control system changes the caster angle by grasping the state using a vehicle speed sensor, steering sensor, steering angle sensor at the neutral position, etc., and sending this information to the controller to control the caster variable actuator. It is designed to let you do so. As the vehicle speed increases, the caster trail is increased to ensure straight-line performance, and during steering, the caster trail is decreased to ensure steerability.

Further, conventionally, there is no structure in which the caster trail is enlarged during braking to further improve braking performance.

(Problems to be Solved by the Invention) As described above, the conventional caster trail control system includes a vehicle speed sensor, a steering sensor, a steering angle sensor at a neutral position,
The caster variable actuator is controlled by the controller and the caster variable actuator, making the configuration complicated and costly.Furthermore, it is not possible to control the caster trail during braking, making it impossible to improve braking performance. .

This invention was made based on the above-mentioned circumstances, and its purpose is to improve running performance by improving straightness and steering performance while having a simple and economical configuration that utilizes the currently used system. The present invention aims to provide a caster trail control system that can reduce the cost and maintain sufficient steering performance even if the capacity of the power steering pump is lowered than the current level. It is something.

[Structure of the Invention (Means for Solving the Problems)] This invention includes a variable caster actuator for varying the caster angle, and a variable caster actuator connected to the variable caster actuator to control the pump pressure of the power steering system and the master cylinder of the brake system. A caster trail control valve that is switched by pressure and operates the caster variable actuator so that the caster trail is increased when traveling straight, the caster trail is decreased when steering, and the caster trail is increased during braking. It is.

(Operation) This invention switches the caster trail control valve and operates the caster variable actuator using the pump pressure of the power steering system and the pressure of the master cylinder of the brake system, making it easy to adapt to the system currently in use. This eliminates the need for conventionally required vehicle speed sensors, steering sensors, neutral position steering angle sensors, controllers, etc., making it possible to simplify the configuration and reduce costs.

In addition, the variable caster actuator is configured to operate to increase the caster trail when driving straight, reduce the caster trail when steering, and increase the caster trail during braking, which improves straight-line performance and steering performance, thereby improving driving performance. Not only that, but it also makes it possible to improve braking performance, which was not possible in the past.

Furthermore, since steering performance is improved by controlling the caster trail, sufficient steering performance can be maintained even if the power steering pump capacity is lowered from the current level, and costs can be reduced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of the present invention, where 1 is a caster trail control system, 2 is a power steering system, and 3 is a brake system.

The caster trail control system 1 includes a caster variable actuator 4. The variable caster actuator 4 has an actuation shaft 7 that is integrated with a piston 6 housed in a cylinder 5, and the tip of the actuation shaft 7 is connected to the upper end of a front-side suspension device 8 that is supported so as to be movable in the horizontal direction. 8a.

Further, the first chamber 5a of the cylinder 5 partitioned by the piston 6 of the caster variable actuator 4 is connected to the fifth connection port (2) of the caster trail control valve 10 via the piping 9 and to the caster trail control valve via the piping 11. It is in a state where it is connected to the sixth connection port (2) of No. 10. Further, the spring 12 is housed in the second portion M5b. Then, the suspension device 8
The inclination angle, that is, the caster angle, is changed so that the caster trail L is changed.

The caster trail control valve 10 also has a first connection port connected to the power steering system 2 in addition to the fifth and sixth connection ports (1) and (2) connected to the caster variable actuator 4. Second. Third. It has seventh connection ports ■, ■, ■, ■, and a fourth connection port ■ connected to the brake system 3. Further, an eighth connection port (■) that communicates with the first connection port (■) as described later, and the third connection port (■)
As will be described later, a ninth connection port (2) is provided.

The power steering system 2 also includes a power steering control valve 23 to which a piping system 22 including a power steering pump 20 and a reserve tank 21 is connected, and the power steering control valve 23 is further connected to piping 24. The actuator 26 is connected to the actuator 25 via the steering wheel 25, and the angle of the wheel 27, that is, the steering angle, is changed in accordance with the rotation of a handle (not shown). Note that this power steering system 2 itself is well known, so a detailed explanation will be omitted.

Further, a pipe 28 is branched from the pipe 24 connected to one end side of the actuator 26 of the power steering system 2, and this pipe 28 is connected to the third connection port (2) of the caster trail control valve 10. It has become. Further, a pipe 29 is branched from the pipe 25 connected to the other end side of the actuator 26, and this pipe 29
is connected to the first connection port (2) of the caster trail control valve 10.

Furthermore, the power steering pump 2 of the piping system 22
0 and the power steering control valve 23
A pipe 30 is branched from 2a, and this pipe 30 is connected to the second connection port (2) of the caster trail control valve 10. Further, the reserve tank 21 of the power steering system 2 and the seventh connection port (2) of the caster trail control valve 10 are connected via a pipe 31.

Further, a pipe 32 is branched from the pipe 29 connected to the first connection port (3) of the caster trail control valve 10, and this branched pipe 32 is connected to the caster trail control valve 10.
It is in a state where it is connected to the eighth connection port (2). Further, a pipe 33 is branched from the pipe 28 connected to the third connection port (3) of the caster trail control valve 10, and this branched pipe 33 is connected to the ninth port of the caster trail control valve 10.
It is connected to the connection port ■.

The fourth connection port ■ of the caster trail control valve 10
is connected to a master cylinder 37 of the brake system 3 via a pipe 36 equipped with a check valve 35.

Further, a pipe 38 is branched from a pipe 36a connecting the check valve 35 and the master cylinder 37, and this branched pipe 38 is connected to the first connection port a of the pressure valve 40. Further, a pipe 41 is branched from the pipe 36b connecting the fourth connection port (1) of the caster trail control valve 10 and the check valve 35, and this branched pipe 41 is connected to the second connection port of the pressure valve 40. It is connected to. Furthermore, the third connection port C of the pressure valve 40 is connected to the reserve tank 43 via a pipe 42.

Note that the brake system itself is well known, so a detailed explanation will be omitted.

Further, as shown in FIG. 2, the caster trail control valve 10 has valve bodies 51 and 52 housed in a valve body 50, and a first chamber of the valve body 50 partitioned by the valve body 51. 50a is connected to the piping 29 from the power steering system 2 side through the first connection port (■), and the second portion M50b is connected to the piping 28 from the power steering system 2 side through the third connection port (■). is connected.

Springs 55 and 56 are housed in the first chamber 50a and the second chamber 50b, and actuator 2 of the power steering system 2 during non-steering, such as when traveling straight.
There is no pressure difference in the pipes 24 and 25 leading to the first chamber 50.
When the pressure in a and the second chamber 50b is the same, the valve body 5
1 maintains the neutral position, and when a pressure difference occurs between the first chamber 50a and the second chamber 50b due to steering, the chamber is displaced to the one with the weaker pressure.

Further, the third valve body 50 partitioned by the valve body 52
A spring 57 is accommodated in the chamber 55c, and a pipe 36 from the brake system 3 side is connected to the third chamber 55d via a fourth connection port (2). As will be described later, when hydraulic pressure is applied to the fourth chamber 55d during braking, the valve body 52 is displaced toward the third chamber 50c against the biasing force of the spring 57.

When the vehicle is not being steered, such as when traveling straight, the piping 24 leads to the actuator 26 of the power steering system 2.
．． Since there is no difference in pressure between the two chambers 50a and 25, the first chamber 50a
The pressure between the valve body 5 and the second chamber 50b is balanced, and the valve body 5
1 remains in the neutral position by springs 55 and 56. At this time, the second connection port (2) and the sixth connection port (2) are in communication with each other. In addition, the piping 24 that leads to the actuator 26 of the power steering system 2 with the steering
．． When there is a difference in the pressure between the first chamber 50a and the second chamber 50b, the valve body 51 is displaced toward the lower pressure chamber. At this time, the sixth connection port (2) and the eighth connection port (2), or the sixth connection port (2) and the ninth connection port (2) are brought into communication.

Further, when the valve body 52 is displaced against the biasing force of the spring 57 during braking, the sixth connection port 0 is closed by the valve body 57, and the fifth connection port 7
The connection port ■ is now in communication.

FIG. 3 shows the configuration of the pressure switch 40.
A valve body 60 houses a valve body 61 and a spring 62, and during non-braking operation, the valve body 6
The small diameter portion 61a of the first port is in communication with the second connection port C and the third connection port C, and when pressure is applied to the master cylinder 37 due to braking operation and the pressure in the chamber 60a increases, the valve closes. The structure is such that the body 61 is displaced against the biasing force of the spring 62 and closes the flow path.

FIG. 4 shows the relationship between the pump pressure P of the power steering pump 20 and the vehicle speed V. In the case of this embodiment, a description will be given of the case where the pump pressure P decreases as the vehicle speed V increases.

Next, with reference to FIGS. 5 and 6, the control state of the caster trail L during straight acceleration will be described. First, when the vehicle is traveling straight, the power steering system 2 is not operating, and there is no difference in pressure between the pipes 24 and 25 to the actuator 26 of the power steering system 2. As a result, as described above, the valve body 51 of the caster trail control valve 10 maintains the neutral position, and since the brake system 3 is not operating, the valve body 52 is pushed back by the spring 57, and the second connection port■
and the sixth connection port (2) are in communication with each other. (See FIG. 6) On the other hand, as the vehicle speed V increases with acceleration, the pump pressure P of the power steering pump 20 decreases as described above with reference to FIG. Thereby, a pipe 30 branched from the pipe 22a connected to the power steering pump 20 of the power steering system 2, a flow path connecting the second connection port (■) and the sixth connection port (■) of the caster trail control valve 10, and The pressure in the chamber 5a of the caster variable actuator 4, which is communicated sequentially through the plumber 1, becomes Pl lower than the pressure P in the neutral position shown in FIG. As a result, the piston 6 to which the operating shaft 7 of the variable caster actuator 4 is connected moves from the neutral state in FIG. 1 to the left in the figure.

The upper end 8a of the suspension device 8 connected to the operating shaft 7
is displaced to the left (in the direction of arrow A), and the caster trail L is set to be larger than the normal caster trail (L, >L). This makes it possible to ensure better straightness.

Next, the control state of the caster trail L during steering will be explained with reference to FIGS. 7 and 8. First, when the power steering system 2 is activated as a result of steering, and a difference occurs in the pressure in the pipes 24 and 25 to the actuator 26 of the power steering system 2, as described above, the valve body 5 of the caster trail control valve 10
1 is displaced to the side of the room with lower pressure. For example, piping 2
If the pressure in the pipe 25 is higher than the pressure in the first
The pressure in the second chamber 50a becomes higher than the pressure in the second chamber 50b, and the valve body 51 moves to the left in the state shown in FIG.
(in the direction of the arrow).

Further, since the brake system 3 is in a non-operating state, the valve body 52 is in a state where it is pushed back by the spring 57. Then, the sixth connection port (2) and the eighth connection port (2) are brought into communication. (See Fig. 8) If the handle is turned in the opposite direction, the pressure in the pipe 24 becomes higher than the pressure in the pipe 25, and the valve body 51 moves to the right (reversely) in the state shown in Fig. 8. direction), and the sixth connection port (2) and the ninth connection port (2) become in communication with each other.

Then, the pressure of the higher one of the pipes 24 and 25 connected to the actuator 26 of the power steering system 2 is supplied to the chamber 5a of the variable caster actuator 4. That is, when the sixth connection port ■ and the eighth connection port The chamber 5a of the caster variable actuator 4, which communicates with the flow path connecting the sixth connecting port ■, and the pipe 11 sequentially, and the sixth connecting port ■ and the ninth connecting port ■ communicate with each other. In this case, the pipe 28, the pipe 33 branched from the pipe 28, the flow path connecting the ninth connection port (■) and the sixth connection port (■) of the caster trail control valve 10, and the pipe 11 are connected in order. It goes through. Then, the pressure in the chamber 5a of the variable caster actuator 4 becomes P2, which is higher than the pressure P in the neutral position shown in FIG.

As a result, the operating shaft 7 of the caster variable actuator 4
The piston 6 to which the piston 6 is connected moves from the neutral state shown in FIG. 1 to the right in the drawing. Then, the upper end 8a of the suspension device 8 connected to the operating shaft 7 is displaced to the right (in the convex direction of the arrow), and the caster trail is changed from the normal caster trail to the smaller caster trail L.
2 (L2 >L). This ensures better steering performance.

Next, the control state during braking will be explained with reference to FIGS. 9 to 11. First, as pressure is applied to the master cylinder 37 due to braking, the valve body 61 of the pressure valve 40 is displaced against the biasing force of the spring 62 as shown in FIG. The flow path communicating with the connection port C is closed. This causes the pressure in the master cylinder 37 to increase to the fourth position of the caster trail control valve 10.
, and the pressure in the fourth chamber 50d increases. Then, the valve body 52 resists the urging force of the spring 57 and the first
Displaced in the two directions of the arrows in Figure 1, the fifth connection port (■) and the seventh connection port (■) of the caster trail control valve 10 communicate with each other,
The part m5a of the variable caster actuator 4 is connected to the fifth connection port of the piping 9 and the caster trail control valve 10.
It is in a state where it is connected to the reserve tank 21 of the power steering system 2 via the flow path connecting the and the seventh connection port (2) and the piping 31 in this order.

As a result, the part Fiz of the caster variable actuator 4
5 The oil in a leaks to the reserve tank 21 side and enters room 5.
The pressure inside a becomes high P3, which is lower than the pressure P in the neutral position shown in FIG. As a result, the piston 6 to which the operating shaft 7 of the caster variable actuator 4 is connected is moved by the spring 1.
Due to the biasing force 2, it moves from the neutral state shown in FIG. 1 to the left in the drawing. Then, the upper end 8a of the suspension device 8 connected to the operating shaft 7 is displaced to the left (arrow width direction), and the caster trail L1 (Ll) is larger than the normal caster trail.
>L). This ensures better braking performance.

As described above, according to the above embodiment, the caster trail control valve is switched by the pump pressure of the power steering system and the pressure of the master cylinder of the brake system to operate the caster variable actuator. System 1 and brake system 3 only require a simple mechanism to be added to the system, eliminating the need for the vehicle speed sensor, steering sensor, neutral position steering angle sensor, controller, etc. that were previously required, simplifying the configuration and reducing costs. Cost reduction becomes possible. In addition, the variable caster actuator is configured to operate to increase the caster trail when driving straight, reduce the caster trail when steering, and increase the caster trail during braking, which improves straight-line performance and steering performance, thereby improving driving performance. Not only that, but it also makes it possible to improve braking performance, which was not possible in the past. Furthermore, since steering performance is improved by controlling the caster trail, sufficient steering performance can be maintained even if the power steering pump capacity is lowered from the current level, and costs can be reduced.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made without departing from the gist.

[Effects of the Invention] As detailed above, according to the present invention, although it is a simple and economical configuration that utilizes the currently used system,
It is possible to improve driving performance by improving straight running performance and steering performance, and it is also possible to further improve braking performance.
The present invention has the effect of providing a caster trail control system that can maintain sufficient steering performance even if the power steering pump capacity is lower than the current level, and that can reduce costs.

[Brief explanation of the drawing]

The drawings are for explaining one embodiment of the present invention; FIG. 1 is a diagram schematically showing the configuration, FIG. 2 is a schematic diagram of the caster trail control valve, and FIG. 3 is a schematic diagram of the pressure valve. Fig. 4 is a diagram showing the relationship between vehicle speed and power steering pump pressure, Fig. 5 is an explanatory diagram showing the caster trail control state during straight acceleration, and Fig. 6 is a diagram showing the caster trail control state during straight acceleration. FIG. 7 is an explanatory diagram showing the operating state of the control valve. FIG. 7 is an explanatory diagram showing the caster trail control state during steering. FIG. 8 is an explanatory diagram showing the operating state of the caster trail control valve during steering. Diagram showing the operating state of the pressure valve during braking, No. 10
This figure is an explanatory view showing the caster trail control state during braking, and FIG. 11 is an explanatory view showing the operating state of the caster trail control valve during braking. 1... Caster trail control system, 2... Power steering system, 3... Brake system,
L, L,, L2... Caster trail.

Claims (1)

[Claims] A variable caster actuator is used to vary the caster angle, and the variable caster actuator is connected to the variable caster actuator and is switched by the pump pressure of the power steering system and the pressure of the master cylinder of the brake system, increasing the caster trail when driving straight and decreasing the caster trail when steering. A caster trail control system comprising: a caster trail control valve that operates the variable caster actuator to increase the caster trail during braking.