Land vehicles: bodies and tops – Tops – Let-down type top
Reexamination Certificate
1999-09-02
2001-08-14
Dayoan, D. Glenn (Department: 3612)
Land vehicles: bodies and tops
Tops
Let-down type top
C296S117000, C060S431000
Reexamination Certificate
active
06273492
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an operating mechanism for a folding top of a convertible with a hydraulic gear mechanism having a hydraulic pump and hydraulic motors connected in an articulated manner to the folding top, with a position transmitter for generating electric signals according to the position of the folding top and with control electronics for producing the intended sequence of movements of the folding top and for sensing the electric signals of the position transmitter.
Such operating mechanisms are frequently used in modern convertibles and are consequently known. In these cases, the hydraulic motors, usually designed as hydraulic cylinders, are controlled by means of electromagnetically switchable hydraulic valves. The limit switches are arranged at the ends of the range of movement of the folding top and, when the folding top reaches its end position, send a signal to the control electronics. In order to switch the hydraulic valves at the intended positions of the folding top, further limit switches are frequently arranged within the range of movement of the folding top. The speed of the folding top during opening and closing is dictated by the dimensions of the linkages of the folding top and the volumetric flow/delivery characteristic of the hydraulic pump. In these cases, even minor changes to the structural design of the folding top lead to distinct changes in the speed of movement of the folding top.
A disadvantage of the known operating mechanism is that the adaptation of the linkage to the intended speed of movement of the folding top is very complex. Furthermore, the movement of the folding top is very jerky and slow.
SUMMARY OF THE INVENTION
The invention is based on the problem of designing an operating mechanism of the type stated at the beginning in such a way that the movement of the folding top can be adapted to an intended speed with particularly low structural expenditure.
This problem is solved according to the invention by it being possible for a volumetric flow of hydraulic medium of the hydraulic pump or a hydraulic output of the hydraulic medium to be regulated by the control electronics for producing an intended speed of movement of the folding top.
This type of design allows the speed to be continuously adapted in a simple manner during the moving of the folding top by regulating the volumetric flow of the hydraulic pump. Thanks to the invention, the range of movement of the folding top can be subdivided into a plurality of positional ranges by the use of a plurality of limit switches and for a predetermined speed to be set for each positional range by regulating a corresponding volumetric flow. The speed can therefore be changed independently of the dimensions of the linkage. With the operating mechanism according to the invention, moreover, various types of folding top can be actuated. This leads to a very short development time for a new folding top.
The volumetric flow of the hydraulic medium could be regulated, for example, by means of a stepless gear mechanism between the hydraulic pump and an electric motor driving the latter. It would also be conceivable to use a hydraulic pump with a variable displacement volume. The operating mechanism according to the invention requires particularly low structural expenditure, however, and is particularly inexpensive if the rotational speed of an electric motor driving the hydraulic pump can be regulated.
The adaptation of the operating mechanism according to the invention to different types of folding top is particularly inexpensive if the control electronics have a memory for a plurality of rotational speeds or rotational-speed profiles of the electric motor intended for various positions of the folding top. As a result, the rotational speeds and rotational-speed profiles of the electric motor are stored as software and can therefore be easily changed.
A plurality of limit switches advantageously sense the position of the folding top, each range between two limit switches being assigned a constant rotational speed or constant output of the electric motor.
The limit switches serve as interpolation points for the positional detection. In another configuration, the rotational speed of the motor is integrated over time between these interpolation points. Consequently, the position between the interpolation points can be interpolated. Here too, a rotational-speed or PWM setpoint selection is specified for the electric motor according to the position.
It could be considered to use many limit switches to subdivide the overall movement of the folding top into numerous positional ranges and to change the rotational speed of the electric motor respectively in the positional ranges. However, this requires a high number of limit switches. According to another advantageous development of the invention, however, a high number of limit switches can be avoided if the control electronics have means for calculating the position of the folding top at any given instant. In this way, the approximate position of the folding top can be calculated by the control device from the number of revolutions of the electric motor and the average displacement volume of the hydraulic pump. Therefore, only a particularly small number of limit switches are required for interpolation points to calculate the position of the folding top. A further advantage of this type of design is that it is no longer necessary for the folding top to move at a different speed whenever there is a signal from one of the limit switches, but instead the speed can be varied continuously. This type of design makes it possible to avoid jerky movement of the folding top.
According to another advantageous development of the invention, the means for calculating the position of the folding top at any given instant require particularly low structural expenditure if the control electronics are designed for determining the position of the folding top at any given instant from the number of revolutions of the electric motor and the volumetric efficiency of the hydraulic gear mechanism.
It helps to increase further the accuracy in the determination of the position of the folding top if the electric motor senses the angular position or speed of the rotor of the folding top and if the control electronics are designed for calculating the position of the folding top on the basis of the rotor position or rotor speed.
According to another advantageous development of the invention, the position of the folding top at any given instant can be determined particularly accurately by a sensor for sensing an adjusting angle or adjusting displacement of a linkage of the folding top. In this case, the sensor can, like a potentiometer for example, generate an analog signal or scan and count markings on the linkage. This type of design permits virtually any desired changes in speed during moving of the folding top, with a particularly small number of limit switches. A rotational-speed or PWM setpoint selection for the electric motor is specified according to the position.
The operating mechanism according to the invention is particularly inexpensive in the case of DC motors with brushgear if the control electronics are designed for sensing and counting voltage and current peaks. These are produced, for example, by a Hall generator or by commutation of the motor (ripple counting).
In the calculation of the position of the folding top on the basis of the revolutions of the electric motor, the changing of the hydraulic efficiency of the hydraulic gear mechanism leads to errors. According to another advantageous development of the invention, these errors can be kept particularly low by means of sensors for the pressure and temperature of the hydraulic medium.
According to another advantageous development of the invention, the error in the sensing of the position of the folding top can be further reduced with particularly low expenditure if the control electronics have a memory for an average number of revolutions of the electric motor for a movement
Baumert Jochen
Schroder Hans-Joachim
Coletta Lori L.
Dayoan D. Glenn
Farber Martin A.
Mannesmann VDO AG
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