Drive gear selection arrangement for an automatic transmission

A space and weight-saving drive gear selection arrangement for an automatic transmission is configured clearly for the driver, is simple to install and can be operated without a significant application of mechanical force. For this purpose, the drive gear selection has a knob which is positioned centrally in a circular or elliptical display panel. The display panel has a first section with the selection positions for the drive conditions P, R, N and D which can be selected by the knob. Arranged in a second portion of the display panel is an information panel in which operating instructions for the driver or information regarding the operating state of the transmission can be displayed.

BACKGROUND OF THE INVENTION 
This invention relates to multifunctional drive gear selection arrangement 
for automatic transmissions. 
Conventional drive gear selection arrangements signal the gear desired by 
the driver of a motor vehicle to a transmission control unit which selects 
the desired gear in the transmission by driving electrohydraulically 
actuatable control valves. Typically, drive gear selectors of this kind 
are designed as a selector lever which can be moved angularly in a gear 
selection slot so that one of several gear selection positions, for 
example, P, R, N, D1, D2 and D3 can be selected mechanically. 
U.S. Pat. No. 4,905,530, for example, discloses a gear selection 
arrangement for an automatic transmission which can be controlled by an 
electronic control unit in which a manually operated gear selection lever 
can be moved to select one of the above-mentioned gears by moving the 
selector lever angularly in a first gear selection slot. The selector 
lever may also be switched through a transverse slot into a second gear 
selection slot in which the selector lever can be moved angularly by the 
driver to manually select a desired forward gear, for example, D1, D2 or 
D3. 
The magazine, Automobil Revue No. 29 (14th Jul., 1994), page 19, describes 
a gear selection arrangement for an automatic transmission of a motor 
vehicle in which rocker switches are arranged on the spokes of the vehicle 
steering wheel by which it is possible to shift up or down in the 
forward-gear range of the transmission. 
Finally, U.S. Pat. No. 5,094,115 discloses a gear selection arrangement for 
automatic transmissions in which a drive gear switch is arranged on the 
steering column in the immediate vicinity of the steering wheel. This 
drive gear switch is an essentially cylindrical rotary switch having a 
finger actuation surface projecting perpendicularly from its cylinder 
circumference which can be depressed to select a transmission drive gear. 
Pushbuttons are arranged on the finger actuation surface for the 
activation and deactivation of different transmission operating modes. A 
section of a hollow cylinder arranged for rotation about the axis of the 
cylindrical drive gear switch and spaced from the cylindrical drive-gear 
switch displays the selected gear. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a drive 
gear selection arrangement which overcomes disadvantages of the prior art. 
Another object of the invention is to provide a space and weight-saving 
drive gear selection arrangement which can be operated easily and without 
substantial mechanical effort by the driver. 
A further object of the invention is to provide a drive gear selection 
arrangement in which the selected transmission condition or the selected 
drive gear is clearly displayed to the driver of the vehicle so that the 
driver can read important information from the device. 
These and other objects of the invention are attained by providing a drive 
gear selection arrangement which transmits mechanical or electrical 
signals to a transmission control unit. The drive gear selection device 
preferably includes an essentially circular or elliptical display panel in 
which a knob for selecting individual drive gear selection positions, such 
as P, R, N, D1, D2 and D3, has a centrally positioned axis and is 
connected to a transmission control unit through an electrical or 
mechanical signal generation or transmission system which may include, for 
example, electric switches or Bowden cables. In the display panel, the 
selection positions of the drive gears of the transmission are arranged in 
an upper circular or elliptical portion, while a selectively activatable 
information panel is positioned in a lower portion to indicate to the 
driver when a forward gear D1-D3 or the reverse gear R is chosen or that 
the brake of the motor vehicle must be actuated before the desired gear 
can be engaged. However, it is also possible to use the selectively 
activatable information panel to display other transmission-relevant 
information to the driver, for example the activation of a sporty or 
economy gear change program. To attract the attention of the driver more 
effectively, provision can be made for the entire display panel or just 
the letters or the display symbols to flash on and off. 
In an advantageous embodiment of the invention, a momentary contact switch 
can be arranged on the knob by which the forward gears D1-D3 can be 
selected in a rising or falling sequence. This momentary contact switch is 
preferably in the form of a tipswitch. In this embodiment of the drive 
gear selection device only a selection position D is provided as forward 
drive indication on the first display panel for the drive gears of the 
transmission, and a further display panel is arranged next to the D 
selection position. The forward gears chosen by the momentary contact 
switch are displayed optically on this additional display panel.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In the typical embodiment of the invention illustrated in FIG. 1, a drive 
gear selection device 1 has a circular design and includes at its center a 
knob 2 for selecting the gear selection positions for the transmission 
conditions park (P), reverse (R), neutral (N) and forward travel (D). 
These selection positions for the drive gears are distributed 
approximately in an upper semicircle around the axis of rotation of the 
knob 2 in a display panel 6. In the exemplary embodiment shown here, the 
knob 2 includes a tipswitch 3. When the drive position D is selected by 
the knob 2, the tipswitch 3 may be activated to shift up or down into any 
of the individual forward gears D1, D2 and D3. Arranged at the right of 
the display panel next to selection position D for the forward drive 
condition, there is an additional display section 4 in which the selected 
forward gear D1, D2, D3, or the associated number 1, 2 or 3, is displayed 
as shown in FIG. 1. 
In another typical embodiment, shown in FIG. 2, the individual forward 
drive gear display section 4 is omitted and the single knob position D is 
replaced by three knob positions D1, D2 and D3 which can be selected by 
rotation of the knob 2 about its axis. The tipswitch on the knob 2 is 
likewise omitted in this embodiment of the invention. 
In both of the illustrated embodiments of the invention, an information 
section 5 is provided in a lower portion of the display panel 6, and 
various operating instructions or functional states of the transmission 
can be displayed for the driver in this section. As illustrated in the 
drawings, this display section can, for example, provide an instruction to 
operate the brake which is preferably lighted whenever the driver selects 
a forward or reverse gear drive position D or R. It is furthermore 
possible to illustrate other transmission-relevant information in the 
information section 5. Provision can preferably be made for the 
information section itself, or the letters or symbols displayed in it, to 
flash on and off. 
Although the invention has been described herein with reference to specific 
embodiments, many modifications and variations therein will readily occur 
to those skilled in the art. Accordingly, all such variations and 
modifications are included within the intended scope of the invention.