JP2623364B2 - Steering simulator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering simulator used for testing a power steering used in an actual automobile and for developing the power steering.

2. Description of the Related Art A car travels while maintaining its course by the frictional force between tires and a road surface. The magnitude of the frictional force also varies depending on the running condition and road surface condition of the vehicle.

And, in a car using power steering, the change is transmitted to the driver as a steering response via the power steering, and the magnitude and accuracy of the response are related to the driver's feeling,
It has a great effect on driving ease.

Before developing a power steering system, a bench test is conducted prior to the actual vehicle test, in which a frictional force that slightly changes depending on the running condition of the vehicle and the road surface condition, so-called steering reaction force, is applied in real time. Need to be evaluated.

The steering reaction force is determined by an element proportional to the steering angle, an element proportional to the side slip angle of the vehicle, and other factors.

As shown in FIG. 1, the steering force data when the vehicle actually travels is affected by the inertia of the steering system, friction, the tire slip angle, etc., and is simply proportional to the steering angle or the front wheel turning angle. Not done. In the bench test of the power steering, it is necessary to apply a steering reaction force that reproduces those elements.

However, in a normal bench test, only the steering angle proportional reaction force due to spring force and a constant reaction force due to gravity or hydraulic pressure are applied to the power steering, and the particularly important effect of the tire slip angle is reproduced. I can't.

An object of the present invention is to perform a power steering performance test by applying real-time frictional force, that is, a steering reaction force, which varies delicately according to the running state of a vehicle and road surface conditions, and to a power steering. To provide a steering simulator to be used in the development of a vehicle.

SUMMARY OF THE INVENTION Corresponding to the Problems / Contents of the Claimed Invention In relation to the above problems, a steering simulator of the present invention includes a hydraulic cylinder connected to an output side of a test power steering and generating a steering reaction force. , An electric-hydraulic steering reaction force control valve for controlling hydraulic oil flowing from the oil pump to the hydraulic cylinder, and simultaneously from the hydraulic cylinder to the oil reservoir, and an electric signal of the actuator sensor to input the steering reaction. Calculate the force value,
A computer that outputs the steering reaction force value as a voltage signal, a differentiator that differentiates the electric signal of the actuator / sensor and outputs a correction proportional to the differential value as a voltage signal, and an output of the computer and the differentiator. And an adder for receiving the output of the differentiator prior to the output of the computer to correct the delay of the operation time of the computer. And generating a steering reaction force proportional to the steering angle and the side slip angle, and applying the steering reaction force in real time by the test power steering.

Description of Specific Example Hereinafter, a specified specific example of the steering simulator of the present invention will be described with reference to the drawings.

FIGS. 2 to 11 show a specific example 10 of the steering simulator of the present invention used for evaluating the steering performance of the power steering 30 mounted on a large long cargo truck on a bench. .

The steering simulator 10 is connected to the output side of the power steering 30 to be tested, and a hydraulic cylinder 11 that generates a steering reaction force to apply the steering pressure to the test power steering 30; An electro-hydraulic steering reaction adjustment valve 12 for controlling pressure oil flowing from a pump (not shown) to the hydraulic cylinder 11 and simultaneously from the hydraulic cylinder 11 to an oil reservoir (not shown), and an actuator The computer 13 outputs the steering reaction force value by inputting the electric signal of the sensor 21 and outputs the steering reaction force value as a voltage signal, and differentiates the electric signal of the actuator sensor 21 into a differential value. A differentiator 14 that outputs a proportional correction as a voltage signal, and inputs the outputs of the computer 13 and the differentiator 14 and outputs a voltage signal to the steering reaction force adjusting valve 12. Adder 15 and amplifier 1
6, 17, an analog-digital converter 18, and a digital-analog converter 19.

The hydraulic cylinder 11 is a double rod type double-acting cylinder, and is connected to one end of a rod 23 to a drag link 33 of the test power steering 30 to provide a steering reaction force. Combined with power steering 30.

The hydraulic cylinder 11 includes a cylinder 22 and its cylinder.
Assembled from a piston 24 which is reciprocally slidably fitted into the cylinder 22 and defines a pair of cylinder chambers 25, 26 in the cylinder 22, and the rod 23 fixedly connected to the piston 24, and The cylinder chambers 25 and 26 are provided with a bypass 27 for supplying and discharging hydraulic pressure.

As the steering reaction force adjusting valve 12, a flow control servo valve for controlling the flow rate and pressure of the pressure oil is used, the flapper is displaced between the nozzles by a torque motor, and the nozzle back pressure is changed. The spool of the four-way spool valve is moved, and the movement of the spool is fed back to the flapper by a feedback spring. Of course, the spool valve has a supply port connected to the oil pump, a return port connected to the oil reservoir, and a pair of control ports connected to the bypass 27 of the hydraulic cylinder 11. Assembled to the hydraulic cylinder 11.

The computer 13 has the actuator / sensor
The electric signal of 21 is amplified by the amplifier 17 and converted by the analog-digital converter 18 and input to the input circuit, while the calculated steering reaction force value is output as a voltage signal from the output circuit, Then, it is electrically connected where it is converted by the digital-analog converter 19 and input to the input side of the adder 15.

In the computer 13, the side slip angle of the front wheel tire is solved in real time by simultaneously balancing the lateral movement and the rotational movement of the vehicle. In particular, in this case,
A three-degree-of-freedom two-wheel vehicle model in which the balance of the front-rear force, the balance of the lateral force, and the balance of the moment about the vehicle center of gravity are considered, and the vertical, roll, and pitch are ignored. That is, the calculation is handled as a model in which the right and left wheels are shifted toward the center of the vehicle. FIG. 3 shows the motion model diagram, but since the equations are known, only the outline is shown below.

Lateral mU (dB / dt + γ) = Fyf + Fyr Moment Idγ / dt = If · Fyf−Ir · Fyr Front wheel βf = β + If · γ / U−δ Rear wheel βr = β−Ir · γ / U The calculated vehicle behavior is stored in the hard disk, and the vehicle characteristics can be analyzed based on the memory.

In this way, when the slip angle of the front wheel tire is obtained, the slip angle is multiplied by the cornering power of the front wheel to obtain the cornering force of the front wheel (the point of application is a in FIG. 4). Multiplying the moment arm obtained as the sum of the trail (b in FIG. 4) and the pneumatic trail (c in FIG. 4) to obtain the restoring torque of the front wheels. The restoring torque generated by the front wheel king pin tilt angle is added to this restoring torque. Further, the toe-in (A in FIG. 5) which controls the delicate steering feeling in the vicinity of straight ahead, the solid friction force of the linkage in the power steering 30 (see FIG. 5). B) in FIG. 5 and a torque (C in FIG. 5) for lifting the sprung caused by the king pin tilt angle are added to calculate a steering reaction force value for the power steering 30.

In this manner, the steering reaction force value calculated by the computer 13 takes into account a model of an element that affects the steering reaction force as shown in FIG.

Also, when the side slip angle is actually obtained, the computer 13 obtains the cornering force and the self-aligning torque at that time from tire data stored in advance, and simplifies the calculation. I have.

Further, the computer 13 captures the displacement of the linkage of the power steering 30 as a signal,
The change in the vehicle motion state is calculated by the Euler method every 12.5 msec, and the average of the four times is used to calculate the A / D and D values between the sensor, computer and actuator.
A method is adopted in which the steering reaction force value is output as a command to the hydraulic cylinder 11 every 50 msec including the required / A conversion time.

As a result, the hydraulic cylinder 11 receives the command and generates a steering reaction force, and at that time, the generated steering reaction force already has a delay of 50 msec, in other words, the hydraulic cylinder 11 Is accompanied by an operation delay of 50 msec.

The differentiator 14 includes a differentiating circuit, and as described above, the output of the computer 13 is delayed by 50 ms, so that the displacement of the linkage of the power steering 30 is differentiated, Correction proportional to the value
The operation is started prior to the command from the computer 13, and functions to avoid a delay in the generation of the steering reaction force, that is, a so-called operation delay of the hydraulic cylinder 11.

This differentiator 14, which functions as such, corrects the steering reaction force value calculated by the computer 13 in the system shown in FIG. Of course, it is clear that it is specifically determined by the system, and the differentiator 14 determines the effective area of the hydraulic cylinder 11, the proportional gain of the amplifier 17, and the proportional gain and the pressure of the steering reaction force adjusting valve 12. Correction is performed by a system constant determined by the initial value of the oil supply flow rate and the like, which is proportional to the differential value of the displacement.

As a result, it is possible to prevent a sense of discontinuity in the steering reaction force. Of course, even if the differentiator 14 is omitted, in the steering simulator 10, the steering reaction force is sufficiently generated in the hydraulic cylinder 11 in real time, and applied to the test power steering 30. .

The adder 15 is formed of an adder circuit including an operational amplifier, and processes and outputs the input provided from the computer 13, the actuator sensor 21, and the steering sensor 20.

Since the output side of the adder 15 is electrically connected to the torque motor of the steering reaction force adjusting valve 12, the output is given to the coil of the torque motor.

The amplifier 16 has its adder 15 and its steering
Between the sensor 20 and the amplifier 17, the computer 17
Each is electrically connected between 13 and its actuator / sensor 21.

The analog-to-digital converter 18 is electrically connected between the computer 13 and the amplifier 17, and the digital-to-analog converter 19 is electrically connected between the computer 13 and the adder 15, respectively.

The steering sensor 20 is located on a drag link 33 connected to a pitman arm 32 at the power steering 30 and is electrically connected to the amplifier 16. The steering simulator 10 also takes into consideration the fact that more accurate and accurate steering reaction force control is enabled by taking in the electric signal of the steering sensor 20.

The actuator sensor 21 is
It is arranged on the eleventh rod 23 and gives the displacement of the rod 23 to the amplifier 17 by an electric signal.

Next, a performance test of the power steering 30 using the steering simulator 10 will be described.

In the steering reaction force adjusting valve 12, since the flapper is located at the neutral position, the spool is located at the neutral position, and accordingly, the piston 24 is also located at the neutral position in the hydraulic cylinder 11, and the oil pump The pressure oil discharged from is returned to the oil reservoir via the supply port and the return port of the steering reaction force adjusting valve 12.

In such a state, when the handle 31 of the power steering 30 begins to rotate, the pitman arm 32 begins to rotate and the drag link 33 begins to move, and at the same time, The rod 23 of the hydraulic cylinder 11 also starts to move together with its piston 24.

The movement of the drag link 33 is sensed by the actuator sensor 21 as the displacement of the rod 23.

The electric signal of the displacement sensed by the actuator / sensor 21 is amplified by the amplifier 17 and the computer 13
And input to the differentiator 14.

The computer 13 calculates the steering reaction force value as described above and outputs it as a voltage signal to the adder 15, while the differentiator 14 calculates the steering reaction force value of the drag link 33 as described above. Correction proportional to the displacement derivative value by differentiating the displacement, prior to the output of the computer 13,
The voltage signal is output to the adder 15.

In the adder 15, the computer 13 and the differentiator
The sum of the inputs given from 14 is output to the torque motor of the steering reaction force adjusting valve 12 as a command for the hydraulic cylinder 11.

The torque motor is driven by the command, the flapper is displaced in the direction corresponding to the handle 31, and the nozzle back pressure moves the spool in the corresponding direction.

In response to the movement of the spool, the supply port is connected to one of the pair of control ports, and the return port is connected to the other of the pair of control ports. The hydraulic cylinder 11 is supplied to the hydraulic cylinder 11 and, at the same time, returned from the hydraulic cylinder 11 to the oil reservoir, and the hydraulic cylinder 11 generates a steering reaction force.

Then, the steering reaction force is transmitted from the rod 23 to the drag link 33 so that the power
Its power steering given to the steering 30
Thirty performance tests were performed in real time.

Figures 6 to 11 show the results of performance tests on steady-state and transient characteristics, in which the steering simulator experiment (hereinafter referred to as bench test) is compared with the large long cargo truck experiment (hereinafter referred to as actual vehicle test). Indicated.

As shown in FIG. 7, the steady-state characteristics are represented by lateral G-steering force data as a comparison with a steady-state value. The steady-state characteristics are in good agreement between the bench test and the actual vehicle test.

On the other hand, the transient characteristics are shown in FIGS. 8 to 11 as a comparison of response characteristics for steering reaction force and yaw rate.
FIG. 8 shows the data of the steering reaction force for the front wheel turning angle, FIG. 9 shows the data of the steering reaction force phase for the front wheel turning angle, and FIG. 10 shows the yaw rate gain for the front wheel turning angle. FIG. 11 is a graph showing the yaw rate phase with respect to the front wheel turning angle. Especially,
Regarding yaw rate, bench test and actual car test agreed well.

As will be apparent from the specific embodiments of the invention described above with reference to the drawings, for one having ordinary skill in the art to which the invention pertains, the subject matter of the present invention will be It derives from the nature and substance of the invention and is readily embodied in another aspect that is objectively recognized as having an inherent nature. Of course, the subject matter of the present invention is commensurate with the subject of the invention and is essential for the establishment of the invention.

Advantages of the Invention As can be understood from the above, the steering simulator of the present invention includes a hydraulic cylinder connected to an output side of a test power steering to generate a steering reaction force,
An electric-hydraulic steering reaction force control valve for controlling hydraulic oil flowing from the oil pump to the hydraulic cylinder and simultaneously from the oil cylinder to the oil reservoir, and an electric signal of the actuator sensor to input the steering reaction force. A computer that calculates a value and outputs the steering reaction force value as a voltage signal, a differentiator that differentiates the electric signal of the actuator / sensor and outputs a correction proportional to the differential value as a voltage signal, and the computer And an adder for inputting the output of the differentiator and outputting the output of the differentiator as a voltage signal to the steering reaction force adjusting valve. And generates a steering reaction force proportional to the steering angle and the sideslip angle, and applies the steering reaction force to the test power steering. Because it provides a more real-time,
According to the steering simulator of the present invention, the frictional force that slightly changes depending on the running state of the vehicle and the road surface condition, that is, the steering reaction force can be reproduced in a bench test with high accuracy, and the power steering performance test becomes more realistic.・ It is carried out in time and is effective in the development of power steering, and it is possible to examine the compatibility between power steering and various vehicles, confirm the performance of new power steering, and identify improvements. As a result, it is very useful and practical for power steering performance testing and development.

[Brief description of the drawings]

FIG. 1 is a graph showing steering force data when the vehicle actually travels, and FIG. 2 is a diagram showing a steering simulator of the present invention used in a performance test of a power steering mounted on a large long cargo truck. Schematic diagram of a specific example,
FIG. 3 is a model diagram of the motion of a large long cargo truck, FIG. 4 is a model diagram of a front axle of the large long cargo truck, and FIG. Model diagram, FIG. 6 is a graph of transient response comparison data of actual vehicle and bench test, FIG.
-A graph of steering force data, Fig. 8 is a graph showing data of a steering reaction force gain with respect to a front wheel turning angle, Fig. 9 is a graph showing data of a steering reaction force phase with respect to a front wheel turning angle,
FIG. 10 is a graph of the yaw rate gain with respect to the front wheel turning angle, and FIG. 11 is a graph of the yaw rate phase with respect to the front wheel turning angle. 11 ... Hydraulic cylinder, 12 ... Electro-pressure steering reaction force adjusting valve, 13 ... Computer, 14 ... Differentiator, 15 ... Adder, 16, 17 ... Amplifier, 18 ... Analog-digital conversion , 19… Digital-to-analog converter, 20… Steering sensor, 21… Actuator sensor, 22…
Cylinder, 30 ... Test power steering.

Claims (1)

(57) [Claims] 1. A hydraulic cylinder connected to an output side of a test power steering and generating a steering reaction force, and hydraulic oil flowing from an oil pump to the hydraulic cylinder, and simultaneously from the hydraulic cylinder to an oil reservoir. An electric-hydraulic steering reaction force control valve for controlling the steering reaction force, a computer for calculating the steering reaction force value by inputting an electric signal of an actuator sensor, and outputting the steering reaction force value as a voltage signal; and the actuator. A differentiator that differentiates the electrical signal of the sensor and outputs a correction proportional to the differential value as a voltage signal, and an adder that inputs the output of the computer and the differentiator and outputs it to the steering reaction force adjusting valve as a voltage signal And a steering simulator including: