JPS5996062A - Synthesized controller with suspension and steering - Google Patents

Abstract

PURPOSE:To permit a variety of combination patterns to be selected by a driver's will or by the desire on designing, by setting a variety of combination patterns corresponding to the traveling conditions in the suspension characteristic and the steering characteristic which determined the operation characteristics. CONSTITUTION:When a power steering is provided, the suspension characteristic is varied by generaging, from a controller 30, the output for operating the solenoids 21b and 22b for varying the damping force of a damper or the solenoids 21a and 22a for varying the spring characteristic or the above-described both, with the aid of the input supplied from a car-speed sensor 31, a manual switch 2, or from the above-described both, and at the same time, the steering characteristic is varied by transmitting the output for controlling the discharge amount of a pump 14 from the controller 30. Therefore, when control is performed so that the relation shown by the lines A and D is obtained according to the variation of the under-steer characteristic, the sporty steering characteristic can be obtained, and when control is performed so that the relation shown by the lines B and C is obtained, gentle steering characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a suspension in which at least one of damper wave characteristics and spring characteristics (hereinafter referred to as suspension characteristics) is variable, and steering characteristics (for example, steering operation force characteristics with respect to front wheel steering angle, In a vehicle equipped with a steering device that has variable steering angle characteristics (such as steering angle characteristics relative to front wheel turning angle), a comprehensive suspension and steering device that controls steering characteristics in accordance with control of the suspension characteristics. It is related to.

2. Description of the Related Art Automobile suspensions have been proposed in which the damping force of a damper is controlled depending on the situation.

For example, as shown in Japanese Utility Model Application No. 55-109008, a vehicle is known in which the damping force is changed depending on the vehicle speed to always obtain favorable handling characteristics. Suspensions consist of a combination of dampers and springs, and it is possible to obtain similar handling characteristics by changing the spring characteristics. These systems strengthen understeer characteristics at high speeds to increase straight-line stability, and weaken understeer characteristics to increase turning performance at low speeds, thereby always providing favorable handling characteristics in response to changes in vehicle speed. Changing the understeer characteristics will change the handling characteristics (steering feel). That is,
If you strengthen the understeer characteristic, the steering force will increase, the steering will become heavier, and the response during steering will become slower. Around 1, when the responsiveness becomes sharper, the response is strengthened.

Moreover, the steering performance can also be changed by changing the steering characteristics. For example, in power steering, changing the steering assist force (assist force), and in manual steering, changing the ratio of the steering wheel steering angle to the front wheel turning angle (hereinafter referred to as the steering reduction ratio). be able to. In other words, if you reduce the assist force with power steering or increase the steering reduction ratio with manual retearing, the stability when driving straight will increase and the steering feel will become dull; When the ratio is made large, or when the ratio is made small in manual steering, the response during steering becomes sharp and the steering sensation becomes sensitive. It is known that the steering operation force is changed, the steering is made heavier at high speeds to improve straight-line stability, and the steering is made lighter at low speeds to improve turning performance.

As mentioned above, in the past, suspension characteristics or steering characteristics were controlled separately to increase straight-line stability during high-speed driving, where lane changes or relatively gentle curves were mostly involved, and to increase straight-line stability during relatively steep turns. Turning performance is increased during low-speed driving where there is a lot of cornering.

However, the senses and preferences of drivers vary greatly, and it is extremely difficult to create a car with performance that satisfies all drivers. For example, in terms of handling characteristics, some people prefer cars with a so-called "Nupotei" feel that responds well to steering operations, while others prefer cars that emphasize stability and have a gentle feel, and there are also elderly people, women, etc. People with less power may prefer lighter steering.

For this reason, if you emphasize the performance of one, you will inevitably sacrifice the other.

In view of the above-mentioned circumstances, the present invention sets several combination patterns of suspension characteristics and steering characteristics that determine handling characteristics depending on driving conditions, and allows the driver to select one of his favorite patterns at will or at the time of design. The purpose is to provide a comprehensive control system for suspension and steering.

A comprehensive control device for suspension and steering according to the present invention includes a suspension unit that suspends a vehicle body on each of the front, rear, left, and right wheels, a steering device that steers a steerable wheel among the wheels, and a damping force or spring constant of the suspension unit. a first control means for variably controlling the damping force ratio or spring constant ratio of the front wheels to the rear wheels by controlling at least one of the above; a second control means for variably controlling the steering characteristics of the steering device; The first 'tf31J is configured to control the steering device in accordance with the control.
It is characterized by comprising a controller that issues a control signal to the control means and the second control means.

According to the present invention, since the steering characteristics can be controlled in accordance with the control of the suspension characteristics, changes in the steering characteristics caused by changing the suspension characteristics and causing the strength or weakness of the understeer characteristics can be controlled by changing the steering leg characteristics. By enhancing or canceling out changes in the steering characteristics that occur, it is possible to obtain steering characteristics that meet various demands. In other words, changes in understeer characteristics caused by the suspension cause a difference in steering feel between dullness and sharpness, but this can be facilitated by the steering characteristics, making it even more dull or sharp, or canceling each other out to make the difference. This allows for a variety of maneuvering characteristics.

Specifically, when the suspension characteristics can be switched to strong or weak understeer by manual switch operation, the steering characteristics are also changed along with this change, so that the change in understeer characteristics can be clearly felt as a human sensation. You can obtain two types of handling characteristics: one that makes you feel it, and one that does not make you feel it. In other words, for example, if you set the steering assist force to be smaller when the power steering is strong, and conversely to increase the assist force when the understeer is weak, then when the suspension characteristic is set to strong understeer using a switch, etc. The tendency for steering force to increase due to stronger understeer is exacerbated by a decrease in assist force, making the steering feel even duller, resulting in a steering characteristic that emphasizes straight-line stability, and vice versa. When this happens, the tendency for steering force to decrease due to weakening of understeer is amplified by the increase in assist force, resulting in a sharper steering feel and a steering characteristic that emphasizes responsiveness. Furthermore, if you set the assist force to be thicker when understeer is strong (and smaller when understeer is weak), the increase or decrease in steering force due to changes in understeer will be offset by the assist force, which is exactly the opposite of the case described above.
The stability or responsiveness of the car is measured according to the understeer characteristics, but the steering feeling is such that the understeer characteristics do not change. It is possible to set the vehicle to have either one of the above two types of handling characteristics at the time of design, or it is also possible to make the changeover possible by means such as a switch that can freely select the driving light.

In addition, not only in the case of power steering but also in the case of manual steering, two types of steering characteristics can be obtained in the same way by changing the steering reduction ratio.

On the other hand, there is a system that automatically controls suspension characteristics in accordance with the driving conditions of the vehicle (eg, vehicle speed, load, steering angle, etc.). If the control characteristics are selected using the above-mentioned → manual switch, etc., there is a problem that the characteristics and characteristics that are excellent in straight-line stability will be inferior when turning, or if the automatic control method is used. This problem can be resolved. In this case as well, two types of steering characteristic cars can be obtained. For example, if the suspension characteristics are controlled to have strong understeer at high speeds and weak understeer at low speeds depending on the vehicle speed, then the assist force of the power steering is reduced at high speeds and the assist force is reduced at low speeds. There are two ways to do it: to make it larger and to do the exact opposite.

The assist force may be small at high speeds and excessively large at low speeds (then either the steering force tends to increase at high speeds due to changes in understeer characteristics and the steering force tends to decrease at low speeds, or the change in assist force is promoted and emphasizes high-speed stability and low-speed turning performance. Therefore, so-called sporty steering characteristics can be obtained.Conversely, if the assist force is large at high speeds and small at low speeds, the tendency of increasing steering force at high speeds and decreasing tendency of steering force at low speeds due to changes in understeer characteristics will increase the assist force. The changes are offset by the understeer characteristics, and the car's condition is designed to provide high-speed stability and low-speed turning performance in accordance with the understeer characteristics, but the steering characteristics are gentle enough that you don't notice it much.

In this case, similar characteristics can also be obtained by changing the steering reduction ratio of manual steering instead of the assist force of power steering.

The characteristics described above can be summarized as shown in the following table.

Table 1 P/S...Power steering M/S...
...Manual Steering The following drawings show details of embodiments of the present invention. FIGS. 1 and 2 respectively show examples of the relationship between centripetal force and yaw rate with respect to steering force when power steering is provided. The one-dot chain line in the figure is a reference line showing the case of manual steering (M/S), and the power steering assist force does not work when the steering force is small, but starts working when it exceeds a certain value. The solid lines (A and C) show an example when the steering assist force is reduced, the broken lines (B and D) show an example when the steering assist force is made jerky, and the upper lines A and B show an example when the understeer characteristic is strengthened. , lower lines C and D show examples where the understeer characteristics are weakened. If control is performed so that the relationship shown by lines A and D is achieved according to changes in the understeer characteristics, sporty handling characteristics will be obtained in case 2 shown in Case 1 above, and the relationship shown by lines B and C will be achieved. When controlled, quiet maneuvering characteristics can be obtained in case ① shown in Table 1.

FIGS. 3 and 4 respectively show the relationship between centripetal acceleration and yaw rate with respect to steering angle when manual steering is provided. The actual fit (a and C) is indicated by the dashed line (if the steering reduction ratio is made thicker).
b and d) show an example when the steering reduction ratio is reduced, the upper lines a and b show an example when the understeer characteristic is strong (when the understeer characteristic is strong), and the lower lines C and d show an example when the understeer characteristic is weak (the case when the understeer characteristic is weak). In this case, as in the case of Figs. 1 and 2, if the control is performed so that the relationship shown by the lines a and d is achieved according to changes in the understeer characteristics, the sporty If the control is performed so that the relationship shown by the lines b and C is obtained, this corresponds to case H, and quiet steering characteristics are obtained.

5 and 6 show an automobile equipped with an integrated control device according to an embodiment of the present invention, in which FIG. 5 shows an embodiment with power steering, and FIG. 6 shows an embodiment with a manual steering wheel. This is an example.

In the embodiment shown in FIG. 5, a solenoid 21b changes the damper wave force in response to input from the vehicle speed sensor 31, the manual switch 32, or both.
, 22b or a solenoid 21 that changes the spring characteristics.
The suspension characteristics are changed by outputting from the controller 30 an output that operates 22a, 22a, or both, and at the same time, the controller 30 outputs an output that controls the discharge amount of the pump 14 to change the steering characteristics. If the power steering pump is engine-driven, this output operates the flow control pulp solenoid.
In the case of electric motor drive, the rotation speed of the motor is controlled.

In the embodiment shown in FIG. 6, a solenoid 2 that changes damper damping force based on input from a vehicle speed sensor 31, a manual switch 32, or both.
By outputting from the controller 3o an output that operates the solenoids 1b, 22b, or the solenoids 21a, 22a, or both of which change the spring characteristics, the suspension characteristics are changed, and at the same time, the controller 3o outputs an output that changes the gear ratio of the steering reduction device 50. Change the delivery steering characteristics.

FIG. 7 shows a main system diagram of an embodiment of the present invention, which is equipped with a power steering system that obtains assist force from a hydraulic pump driven by an engine. The power steering device of this embodiment is equipped with a rack and pinion type steering as manual steering, and a steering shaft 2 rotated by a steering wheel 1 is connected to a pinion 5 via joints 3 and 4. This pinion 5 is meshed with a rack 6, and tie rods 9a, 9b are connected to both ends of this rank 60, which are engaged with knuckle arms sa, sb that are rotatably supported around shafts 7a, 7b. . When the steering wheel 1 is operated and 20 rotations of the steering shaft are transmitted to the rack 6 via the pinion 5, the rack 6
moves in the left-right direction in the figure, and connects to the knuckle arm 8a via tie rods 9a and 9b.

8b, and the steered wheels (generally the front wheels) 10a, 10
Give the rudder angle to b.

The rack 6 has a piston 11c of the power cylinder 11.
is fixed, and pipes 12a and 12b communicating with oil chambers 11a and llb defined by this piston llc are connected to an oil pump 14a via a control pulp 13. The control pulp 13 has been commonly used in power steering devices in this building, and controls the discharge pipe 15 and return pipe 16 of the oil pump 14a to pipes 12a and 12b, respectively, depending on the steering direction.
Alternatively, the hydraulic system is switched to connect to 12b and 12a. For example, when the rack 6 is steered to move rightward in the figure, the discharge pipe 15 is connected to the pipe 12b, and the return pipe 16 is connected to the pipe 12a. As a result, the rightward movement of the rack 6 is assisted by the hydraulic pressure within the power cylinder 11. Furthermore, when the steering shaft 2 is not being rotated, the control pulp 13 allows the discharge pipe 15 and the return pipe 16 to communicate directly with each other, so that the power cylinder 1
Do not send pressure oil to 1.

The oil pump 14a is directly driven by the engine 18 via a belt 17, and a flow rate control valve 19 is interposed in the discharge pipe 15 of the pump 14a. This flow rate control valve 19 includes a valve body 19b that is formed to be slidable in the vertical direction in the figure within a casing 19a, and a valve body 1'9.
The casing 19a is composed of a spring 19C1 that urges b downward in the figure and a flow rate control solenoid 19d, and the casing 19a has bacteria 1 and 2 ports 19e, 19f connected to the discharge pipe 15,
and a third boat 19g connected to the return pipe 16.

When the flow control solenoid 19d is demagnetized, the valve body 1
9b closes the third bow 19g by being pushed by a spring 19c. At this time, the annular groove 19h carved around the valve body 19b fits into the first and second ports 19e and 19f, and these first and second ports 19e.

19f are communicated with each other (the state shown in FIG. 7). On the other hand, when the flow rate control solenoid 19d is excited by the output 30g from the controller 30, the valve body 19b is activated by the spring 19c.
It is pulled upward in the figure against the urging force of. Therefore, the third boat 19g, which had been closed by the valve body 19b, partially communicates with the first port 19e, and
A part of the flow rate from the port 19e returns to the return pipe 16 through the third port 19g, so the flow rate from the second port 19f decreases. That is, the flow control solenoid 19d
During demagnetization, the entire discharge amount of the pump 14a flows to the control pulp 13, resulting in a large steering assist force, and the flow rate control solenoid 19 (when Ha magnetic, part of the discharge amount of the pump 14a is bypassed by the flow lid control valve 19. ,
The flow rate to the control pulp 13 decreases, and the steering assist force decreases. Actually, this solenoid's 0
By changing the N-OFF duty ratio, control as shown in FIGS. 9, 10, and 11, which will be described later, is performed.

The above controller (in addition to input from the power supply, manual switch 32 when switching is possible manually)
input 30a, and the vehicle speed sensor 3 in this embodiment.
1, Reno input 30f (this human power is not limited to vehicle speed, but may also include load, steering angle, etc.) is input, and signals 30 b, 30 that change the suspension characteristics based on these inputs.
c, :30 dOyohi 30e, O and a signal 30g that changes the steering characteristics are output.

Specifically, the steering characteristics are as described above, and regarding the suspension characteristics, for example, the air springs 21, 2
To change the spring characteristics of 2, output 30b from controller 3o.

30c energizes or demagnetizes the solenoids 21a and 22a, and the communication with the actuators 21A and 22A is set to 0N-.
To change the damping characteristics of the damper, the output from the controller 30, 3"Od, 30
This is done by exciting or demagnetizing the solenoids 21b and 22b from eK and changing the orifice size that determines the damper characteristics.

As mentioned above, depending on the vehicle speed (or driving conditions such as load and steering angle), manual switch selection or automatic
It becomes possible to control steering characteristics that follow the suspension characteristics using the controller.

FIG. 8 shows a main system diagram of an embodiment of the present invention, which is equipped with a power steering system that obtains assisting force from a hydraulic pump driven by an electric motor. In this example, the seventh
This embodiment is completely the same as the illustrated embodiment except that the hydraulic pump is driven by a motor rather than an engine, and there is no flow rate control valve, and the same parts are given the same numbers and explanations will be omitted.

In this embodiment, the output 30 from the controller 30 is
The steering characteristics are changed by driving the motor 20 and controlling the discharge amount of the pump 14b by the amount of the pump 14b. Similar to the example shown in FIG. 7, this controller can also change the suspension characteristics, so that mutually related control of the suspension characteristics and steering characteristics is possible.

Figures 9, 10 and 11 are similar to Figures 7 and 8.
It is a graph explaining the relationship between the hydraulic pump discharge amount and the steering characteristic in the case of the example explained in the figure.

The graph in FIG. 9 shows the relationship between the vehicle speed V and the pump discharge amount Q. Generally, at low speeds, that is, when a large steering force is required, the flow rate is large, and as the speed increases, the flow rate decreases, and becomes constant above a certain speed. The difference between the assist force and the small assist force is determined by changing the deenergization/excitation duty ratio of the solenoid of the flow control valve in the embodiment shown in FIG. 7, and by changing the rotational speed of the motor in the embodiment shown in FIG. Vehicle speed v1
At the location, the flow rate changes from QL to morning.

Figure 10 is a graph showing the relationship between the steering torque TH and the oil pressure P when the vehicle speed is above 1, that is, when the flow rate to the power steering is QL and in the morning.The oil pressure P does not change much when the steering torque TH is small. , when the steering torque exceeds a certain value, the oil pressure P increases synergistically. However, in order to obtain the same oil pressure, a larger torque TH is required when the flow rate is QH (lower).

Figure 11 shows the vehicle speed V], that is, the centripetal acceleration and steering torque T when the flow rate to the power steering is QL and proboscis.
This is a graph showing the relationship with H, and the centripetal acceleration increases synergistically as the steering torque TH increases. To obtain the same centripetal acceleration, a vehicle with a higher flow rate requires a larger torque; in other words, the lower the flow rate to the power steering, the smaller the assist force and heavier steering feel.

The embodiment shown in FIG. 12 shows a main system diagram of the present invention when manual steering is provided. In this embodiment as well, parts common to the embodiments shown in FIGS. 7 and 8 are given the same numbers, and their explanations will be omitted.

The upper steering shaft 2a rotated by the steering wheel 1 has a steering reducer 50 and a lower steering shaft 2b.
4, and the rotation of the steering wheel 1 is decelerated by a steering speed reducer 5o, and then rotates the pinion 5. This binion 5 is engaged with a rack 6, and shafts 7a and 7 are attached to both ends of this rack 60.
a knuckle arm 8a rotatably supported around b;
Tie rods 9a and 9b engaged with 8b are connected. The rotation of the binion 5 moves the rack 6 in the left and right directions in the figure, and the knuckle arm 8a is moved through the tie rods 9a and 9b.
, 8b, and the steered wheels (generally front wheels) 10a, 1
Give the rudder angle to 0b.

The above-mentioned steering speed reducer 50 uses the output from the controller 30 to reduce or directly connect the upper steering shaft 2a to the lower steering shaft 2b to transmit rotation, thereby changing the steering characteristics.Details are shown in the enlarged figure. As shown in the figure. Upper steering shirt) 2
A has a gear 51a (tooth i: z1) and an external spline 51b at its lower end, and the gear 51a is connected to the gear 52a (number of teeth = Z2) on the first gear body 52 that rotates freely on the fixed shaft 59. ), and another gear 52b (number of teeth: Z3) on the gear body 52 is connected to the lower steering shaft 2.
b, and meshes with a gear 53a (number of teeth: Z4) of a second gear body 53 having an outer tin 2-in 53b and a gear 53a. Therefore, when rotation is transmitted from the gear 51a at the end of the upper steering shirt 2a to the gear 53a of the second gear body 53, a reduction is performed at a reduction ratio: (Zl/Z2)X(Z3/Z4). Lower steering shaft 2b
The upper end also has an external spline whose axis is aligned with the upper steering shirt 1-2a.
Since the splines 53b of the gear body are adjacent in this order and have the same specifications and are on the same axis, the sleeve 55 having an internal spline that meshes with this spline meshes with any of the three tin lines, and also has the same dimensions as the spline. The top can be slid up and down in the figure. On the other hand, a protrusion (fork) of a shaft 56 that can slide vertically in the reducer case 60 in the groove 55a provided on the outer circumference of this sleeve.
56a is fitted, and the sleeve 55 also moves up and down in alignment with the upper and lower positions of the shaft 56. Furthermore, this shaft 56 is urged downward in the figure by a spring 57, and the solenoid 58 is excited by the output 30g from the controller 30, which overcomes the urging force of the spring 57 and pulls the shaft 56 upward. When the solenoid 58 is demagnetized, it is lowered downward. Therefore, the sleeve 55 moves up and down by energizing and demagnetizing the solenoid 58, and the sleeve 55 moves up and down.
When the solenoid 58 is energized in this figure, the internal spline of the sleeve 55 connects with both the external spline 51b of the upper steering wheel 2a and the external spline 53b of the lower steering wheel 2b. They mesh simultaneously and directly connect the upper and lower steering shafts.

When the solenoid 58 is demagnetized, the shaft 56 and sleeve 55 move downward by the force of the spring 57, and the internal spline of the sleeve 55 connects with the external spline 53b of the second vehicle body 53 and the external tooth of the lower steering shirt 2b. Both splines 54b mesh at the same time, and the rotation of the steering wheel is controlled by the gear train reduction ratio shown in the figure: (Zl /
Z2 ) X (Z3/Z4) is decelerated and the pinion 5 is rotated. As described above, the lenoid 58 is deenergized and excited by the output 30 g from the controller 30, and the steering speed reduction ratio can be changed to change the steering characteristics.

On the other hand, the suspension characteristics can be controlled by the controller 30 according to the driving condition, as in the embodiments shown in FIGS. 7 and 8, and the steering characteristics and suspension characteristics can be controlled in relation to each other by the controller 30. It is.

As explained in detail above, according to the invention, the steering characteristics are also changed in accordance with the control that changes the suspension characteristics, so for example, a sporty steering feeling, a heavy steering feeling, etc. can be achieved. It is now possible to select the vehicle's handling characteristics at the time of design, and to allow the driver to freely select it, which has many advantages for both the designer and the driver.

[Brief explanation of drawings]

1 and 2 are graphs showing the relationship between centripetal acceleration (FIG. 1) and yaw rate (FIG. 2) with respect to steering force in the embodiment of the present invention when power steering is provided; FIGS. 3 and 4 The figure shows centripetal acceleration (Figure 3) and yaw rate (Figure 4) versus steering angle in an embodiment of the present invention with manual steering.
27, 5 and 6 are perspective views showing examples of automobiles equipped with the integrated control device of the present invention. FIG. 5 shows an example of a vehicle equipped with power steering, and FIG. If so, FIG. 7 is a main system diagram of an embodiment of the present invention with power steering by an engine-driven hydraulic pump, and FIG. 8 is a main system diagram of an embodiment of the present invention with power steering by an electric motor-driven hydraulic pump. 9, 10, and 11 are graphs showing the relationship between the hydraulic pump discharge amount and the steering characteristics in an embodiment of the present invention having a power steering system.
Figure 10 is a graph showing the relationship between vehicle speed and pump discharge amount, Figure 10 is a graph showing the relationship between oil pressure and steering torque, Figure 11 is a graph showing the relationship between steering torque and centripetal acceleration, and Figure 12 is a graph showing the relationship between steering torque and centripetal acceleration. It is a main system diagram of an example. 1... Steering wheel 2, 2a, 2b... Steering shaft 3
．． 4...Joint 5...Binion 6...
...Ratsuri 11...Power cylinder 13...Control pulp 14a, 14
b...Hydraulic pump 18...Engine
19...Flow control valve 20...Mo -
Data 21a, 21b, 22a, 22b = - - Reinoid 21A, 22A...Accumulator 30...Controller 31...Vehicle speed sensor □32...Manual switch 50...・
Steering reducer 51a, 52a, 52b, 5
3a...Gear 51b, 53b, 54b
...External tooth spline 55...Slip -
56...Shaft 57...Spring 58...Solenoid Fig. 1 Kou IC sword oJ sword Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] A suspension unit that suspends the vehicle body on each of the front, rear, left and right wheels, a steering device that steers a steerable wheel among the wheels, and a damping force of the suspension unit that controls at least one of a spring constant. a first control means for variably controlling the damping force ratio or spring constant ratio of the front wheels to the rear wheels; a second control means for variably controlling the steering characteristics of the steering device; A comprehensive suspension and steering control device comprising a controller that issues control signals to the first control means and second control means to control the device.