JPH02220976A - Steering system of passenger car with steerable front and rear wheel - Google Patents

Abstract

PURPOSE: To park a passenger car in a small space by providing an electronic control unit, and adjusting, using its switching device, a steering and transmission and setting members for engine fuel supply and for a power brake so that they are operated automatically. CONSTITUTION: An electronic control unit (on-board computer, particularly microprocessor) is provided, and a steering and transmission (advance stage/back stage) and setting members for engine fuel supply and for a power brake are set by the switching device of the unit as follows so as to be automatically operated: on one hand, front and rear wheels are turned in the same direction and at the same strength (angle ratio 1), and up to a normal maximum wheel turning angle of about 45 deg., alternately from one direction to another, while on the other hand the direction of wheel turning is varied at the same time to vary the direction of travel (advance/back). Therefore, an automobile is alternately moved diagonally forward and diagonally backward until being located in a side parking space.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a passenger car having steerable front and rear wheels of the type mentioned in the preamble of claim 1, as is known for example from DE 34 38 084 A1. Regarding the steering system.

In this known steering system, the wheel turning angle of the rear wheels that is initiated when the steering wheel is actuated is basically controlled in the usual manner as a function of the driving speed, ie the rear wheels are controlled in the following manner as a function of the driving speed. It is controlled so that when it is below a predetermined reference value, it is turned in the opposite direction, and when it is above this reference value, it is turned in the same direction with respect to the front wheels. In this case, the magnitude ratio (angular ratio) between the turning angle of the rear wheels and the turning angle of the front wheels changes depending on the driving speed. By configuring the steering system in this known principle, compared to a conventional vehicle with only one controllable vehicle axis, there is a reduction in the turning radius, as it were, and - at low speeds and on very narrow curves - Maneuverability is increased when driving, and - at relatively high travel speeds, improved straight-line driving and considerably better responsiveness to control are achieved.

In the known steering system, a manually operable switching device is additionally provided, with which for low road speed ranges a normal shift of the rear wheels with an angular ratio dependent on the road speed between the front and rear wheel turning angles is provided. It is also possible to stop the deflection in the opposite direction and instead set a fixed, i.e. constant and in particular positive angular ratio, so that the front and rear wheels are swiveled in the same direction.

Parking in a row of vehicles makes it easier for the motorist to park the motor vehicle longitudinally due to the possibility that at low driving speeds the rear wheels may be deflected in the same direction instead of the otherwise normally opposite direction to the front wheels. The robot should be made aware of whether the object should be moved closer to the side or closer to the neighboring object. In this special driving situation with the front and rear wheels turning in the same direction, it is also well thought out to drive the motor vehicle diagonally into the parking space with the so-called "walk or back", which is known especially for industrial trucks and construction vehicles. It will be done.

In known motor vehicles, one of a plurality of fixed angle ratios stored in the on-board computer (microprocessor system) is selected by pressing one of a number of selection buttons as required.

Thereby, as long as the road speed is below a predetermined reference value or, for example, reverse gear or the lowest forward gear is engaged, a control program which is normally executed by an on-board computer causes the rear wheels to move against each other. The control program, which would otherwise have been deflected in the direction, is prevented and instead is selected and fixed and driven with a positive angular ratio if desired, so that the rear wheels are now deflected in the same direction.

The object of the invention is to improve a steering system of the kind initially mentioned in the preamble of the patent claims in order to make parking in tight spaces possible and even simpler.

This problem is solved according to the invention by the features of claim 1.

According to the invention, the front wheels and the rear wheels are therefore swung in the same direction and with the same force when parking or parking into a parking space in a row of longitudinally parked cars, and alternately in one direction and with the same force. The vehicle is turned in another direction, with a change in direction of travel taking place simultaneously with the change in direction of the vehicle turn. The motor vehicle is thus moved alternately diagonally forward and diagonally backward until it is located in a lateral parking space.

This parking process is carried out automatically by manual operation of the switching device, which activates an electronic control unit and a regulating unit, which controls the steering wheel in conjunction with or with the aid of a known microprocessor (on-board computer). and adjusting the setting elements of the transmission, engine fuel supply and power brake, and the front and rear wheels are alternately deflected in the same direction and with the same intensity in one direction and in the other direction, alternating simultaneously with the wheel turning deflection. Then, the lowest forward gear or lowest forward gear and the reverse gear or bank gear of the transmission are engaged, so that the motor vehicle is alternately accelerated to, for example, 2 m/s and then decelerated again.

When changing the direction of travel at the same time, by turning the front and rear wheels alternately in the same direction and with the same force, the car actually turns laterally with respect to its longitudinal direction, as shown in principle in Figure 1. A dog walking or moving backwards. This parking behavior involves rotating the wheels of a motor vehicle by 90 degrees and moving the vehicle laterally, a well-known proposal that cannot actually be realized for passenger cars.
It is clearly more effective than

A motor vehicle equipped with a steering system according to the invention can be parked in narrow spaces. Furthermore, the vehicle can be turned in such a way that the rear of the vehicle or the front of the vehicle does not obstruct flowing traffic. The actual space requirements for the parking stroke are then extremely small both in the longitudinal and lateral directions. In addition to the specific dimensions of the vehicle, the required space for the parking process is of the order of approximately 0.5 m in the longitudinal direction of the vehicle and slightly wider than the width of the vehicle in the lateral direction. In the longitudinal direction, approximately 0.3 aeL is then required for the specific parking or maneuvering drive, whereas approximately 0.3 aeL is required in the forward and rearward directions, respectively, as a safety distance to suit the purpose.
．． It maintains a margin of 111. In the transverse direction, an additional length of about 0.1 m is required for safety and tolerance reasons in a suitable manner, which however can vary from case to case.

The particular effectiveness of the steering system according to the invention when parking in the parking spaces of longitudinally parked rows of cars makes it possible to reduce the (additional) space requirements for otherwise common steering systems and parking methods. This becomes clear when compared with the (additional) space required by this method.

The drawing shows in principle the ratios that occur in parallel parking of passenger cars with various known steering systems and steering methods.

Next, embodiments of the present invention will be described in detail based on the drawings.

The drawings each show the starting position, designated 1, and the end position of a parallel parked passenger car, designated 1', with the steerable front wheels marked 2 and the steerable rear wheels marked 3. . FIG. 1 additionally shows the intermediate position of the vehicle, designated by 1".

A comparison of these figures shows that a passenger car equipped with a steering system according to the invention for a unique parking maneuver when parallel parking is more determined than a passenger car with all-wheel control according to figures 2 to 4 equipped with a known steering system. It is clear that the vehicle requires less space both in the longitudinal direction and in the lateral direction of the vehicle, except for the steering system for diagonal parking in FIG.

A simulated parking experiment with a car approximately 3.65+s long and 1.7 m wide, the controllable wheels of which are turned with a spread of approximately 40' in a parking maneuver, has a steering system according to the invention. The automobile has shown that an additional space requirement of 0.5 m in the longitudinal direction and 1.8 m in the transverse direction is sufficient.

Six changes in the steering angle with corresponding changes in the driving direction were carried out, with longitudinal changes of approximately 0.3 m for specific parking or maneuvering and approximately 0.101 m forward and backward respectively.
was applied as a safety interval.

In contrast, for a vehicle of the same type parked diagonally without a change of direction, corresponding to FIG.
．． There will be a place where 1 meter is secured as a safe distance in front and behind. Laterally there is the same space requirement as in the steering system according to the invention.

In a steering system in which the wheels are turned in the opposite direction with a change of direction according to FIG.
There is an additional space requirement of approximately 3.2 mm in the lateral direction, which is created by widening and turning during parking. This leads to the additional disadvantage that flowing traffic is obstructed or the parking process itself is hindered. The envelope of the parked car is shown by a dashed line, and is 4 to 4'.
It is expressed as

A steering system in which the rear wheels are swiveled with a change of direction according to Figure 4 results in a space requirement of approximately 1.3 m in the longitudinal direction and approximately 3.1 m in the transverse direction, which also corresponds to the space at the rear of the vehicle, also numbered 4. related to the spread and rotation of

The outlay for implementing a steering system according to the invention in a passenger car with steerable front and rear wheels is relatively low. This is because substantially already existing components and electronic control and/or regulating devices can be used. Existing control and regulating devices simply need to be expanded somewhat and, with regard to their program flow, adapted to the existing requirements.

For the automatic flow of the parking process, the onboard computer or corresponding microprocessor must therefore be configured and dimensioned as required without any difficulty for the relevant specialist within the framework of his general expertise. When only one is required and the system is activated appropriately,
Activated by a manually operable switching device.

a) the deflection of the front and rear wheels is controlled in the claimed manner, which in pure technical terms does not differ from a fundamentally reliable electronically controlled four-wheel steering system; b) the driving to be carried out; The drive moment of the propulsion engine for the change of direction is controlled, for which purpose known electronically controlled carburetor and fuel injection systems (so-called E-gas) are applied; C) on the brake pedal; The electronically controlled drive slip control system (AS
R) the application of known brake pressure regulators or modulators as applied within the framework of d) the lowest forward gear or the lowest alternating forward and reversing gears to effect a change in direction of travel; Insertion is controlled.

Interval sensors for close area for replenishment, e.g. ultrasound,
Sensors based on infrared, radar or laser can be applied to scan the size of the parking space and provide appropriate setting signals to the onboard computer.

[Brief explanation of the drawing]

FIG. 1 shows a passenger car having a steering system according to the invention, FIG. 2 shows a passenger car whose steering system allows the front and rear wheels to turn in the same direction during parallel parking without changing direction, and FIG. FIG. 4 shows a passenger car whose steering system has a change of direction and whose front and rear wheels turn in opposite directions; FIG. 4 shows a car whose steering system has a change of direction which turns only its rear wheels. Reference number in the diagram ■... Start position Final position of the car Intermediate position of the car Controllable front wheels Controllable rear wheels Envelope line of the parked car

Claims (1)

[Claims] (1) Using a manually operable switching device, at least 1% between the front and rear wheel turning angles when the driving speed is in a low speed range below the reference value v_0 or when entering reverse gear or low forward gear. A maneuver with two fixed and travel speed-dependent positive angular ratios that is adjustable and thus facilitates parking in a longitudinally parked row of vehicles by turning the front and rear wheels in the same direction. In the steering system of a passenger car with possible front and rear wheels, an electronic control device (onboard computer, in particular a microprocessor) is provided, which controls the steering and transmission (forward gear/reverse gear), engine fuel supply and power. that the setting member of the brake is adjusted for automatic activation as follows;
That is, on the one hand, the front and rear wheels turn in the same direction and with the same intensity (angle ratio 1), but alternately from one direction to another, up to a normal maximum wheel turning angle of approximately 45°. is,
A steering system characterized in that the steering system is adjusted so that the direction of travel (forward/reverse) is changed by simultaneously changing the turning direction of each wheel.