The present invention is directed to a shift-by-wire input unit for controlling a semi-automatic transmission of a vehicle for selecting P, R, N, and D states and for manually shifting gears, comprising a base having an upper surface, four push buttons distributed over the upper surface, each push button associated with one of the transmission states P, R, N, and D and being depressible in an actuation direction perpendicular to the upper surface, and an actuator for manual upshift and downshift.

Conventional input units for a semi-automatic transmission typically comprise a shift lever provided on a centre console of a vehicle which shift lever can be pivoted along a shifting gate including the positions P, R, N and D. Actuators for man ^¬ ual upshift and downshift are typically provided as shift pad ^¬ dles on the steering wheel.

Shift-by-wire input units for a transmission allow a more flexible design. In particular it has been proposed to locate all input elements for a semi-automatic transmission on the centre console of a vehicle. Such input unit which comprises the features of the preamble of claim 1 is described in EP 1 167 831 A2. The shift-by-wire input unit comprises a base and push buttons distributed over an upper surface of the base. Each of the push buttons can be depressed in a direction perpendicular to the upper surface of the base. The four push buttons associated with the transmission states P, R, N and D differ in size and shape to provide a haptic perception of the individual transmission states P, R, N and D. Furthermore, as an actuator for manual upshift and downshift a rocker switch is disposed on the upper surface of the base next to the four push buttons, the rocker switch being depressible on either of two opposite ends in a direction perpendicular to the upper surface of the base to effect manual upshift or downshift, re ^¬ spectively.

Considering performance aspects of shift input units measure ^¬ ment factors can be established, such as number of mode errors made by a driver, for example, first time user (typical situa ^¬ tion for rental cars) , number of glances and glance time (time with eyes-off-the-road) per shift operation. In the course of the present invention it has been observed that input units as described above using push-buttons for the transmission states P, R, N and D and a rocker switch for manual upshift and down ^¬ shift next to the push buttons, which rocker switch is actuat ^¬ ed in the same direction as the push buttons by pressing down in a direction perpendicular to the upper surface of the base does not provide optimal performance characteristics, put a high cognitive load on the user and have a rather high opera ^¬ tion error frequency.

It is an object of the present invention to provide a shift- by-wire input unit for a semi-automatic transmission, which input unit may be operated in a simple, intuitively clear and comfortable manner.

This object is achieved by a shift-by-wire input unit compris ^¬ ing the features of claim 1. Preferred embodiments of the in ^¬ vention are set out in the dependent claims.

According to the present invention the four push buttons are disposed circumferentially distributed around a central finger rest area in an annual arrangement in which adjacent push but ^¬ tons are shifted by 90° around the circumference with respect to each other. The central finger rest area is arranged such that a finger tip of an index finger of a user may be placed thereon. The central finger rest are provides a reference lo ^¬ cation. By moving the finger tip of the index finger from the central finger rest area in opposite directions along a first direction or in opposite directions along a second direction perpendicular to the first direction, the finger tip may be selectively moved to the upper surface of one of the four push buttons which may then be operated by depressing. The actuator for manual upshift and downshift is disposed adjacent to the annular shift button arrangement and is arranged to be movea ^¬ ble for actuation in a direction that is not parallel to the actuation direction of the push buttons, i.e. the actuator has an actuation direction which is not perpendicular to the upper surface of the base.

It has been observed that the annular arrangement of the push buttons around the central finger rest area gives the user a good orientation or reference location when moving the finger tip of the index finger forth or back or laterally to the left or right hand side from the reference location on the central finger rest area to reach one of the push buttons for select ^¬ ing P, R, N or D. It has also been observed that the actuator for manual upshift and downshift can be arranged next to the annular arrangement of the push buttons, but in this case the input performance characteristics are improved by arranging the actuator to be actuated in a direction that is different from the actuation direction of the push buttons for selecting P, R, N and D.

In a preferred embodiment the actuator is a paddle shifter ar ^¬ ranged to be movement forth and back in a direction perpendic ^¬ ular to the actuation direction of the push buttons. This arrangement provides for an intuitively clear differentiation and discrimination between the input elements for P, R, N, and D on the one hand and for manual upshift and downshift on the other hand. In another embodiment the actuator is a rotatable ring dis ^¬ posed around the circular arrangement of push buttons and cen ^¬ tral rest area, which actuator is arranged to be actuated by rotating the ring in clockwise and anti-clockwise direction, respectively .

In a preferred embodiment the upper surface of the push but ^¬ tons and the top surface of the central finger rest area form a concave surface with the central finger rest area being at the lowest level. This arrangement provides an intuitively clear haptic perception for the user when he or she places the finger tip of the index finger on the lowest level in the cen ^¬ tre of the arrangement, and thus gives an easily perceivable feedback that the finger tip is placed in the central rest ar ^¬ ea at the reference location.

In a modified arrangement the upper surfaces of the push but ^¬ tons are arranged concavely such that they lie on a surface of a sphere, whereas the central finger rest area is planar such that the push buttons together with the central finger rest area have a bowl shape with a planar bottom formed by the cen ^¬ tral finger rest area. Also this arrangement provides an intu ^¬ itively clear haptic perception when the finger tip of the index finger is placed in the central rest area at the reference location in the center of the annular arrangement of the push buttons for P, R, N and D.

In preferred embodiments of such concave or bowl-shaped ar ^¬ rangements the central finger rest area and at least parts the upper surfaces of the push buttons are disposed vertically be ^¬ low the surrounding upper surface of the base. In other words the upper surfaces of the push buttons and the central finger rest area form a trough or hollow in the upper surface of the base. This arrangement facilitates placing of the finger tip of the index finger on the central finger rest area in the hollow without looking at the base of the input unit which may for example be located on the centre console of a vehicle. By moving the finger tip to the approximate location of the annu ^¬ lar arrangement of push buttons the user receives confirmation that he or she correctly placed the finger tip of the index finger when the finger tip of the index finger is received in the hollow of the annular arrangement of push buttons at the lowest level of the central finger rest area.

In a preferred embodiment a ridge is provided between each pair of adjacent push buttons, which ridge is extending in ra ^¬ dial direction from an inner periphery of the push button adjacent to the central finger rest area to an outer periphery of the push buttons. Each ridge is protruding vertically above the level of the neighboring push button surfaces to form a tangible separation element between each pair of adjacent push buttons. These ridges separating adjacent push buttons provide a haptic perception that the finger tip of the index finger is placed on an upper surface of one of the push buttons, and not on upper surface areas of two adjacent push buttons in which case the presence of the ridge would be felt by the user. The four separating ridges also serve as haptic guide elements to guide the movement of the finger tip of the index finger to the upper surface of one of the push buttons.

In a preferred embodiment each push button together with the ridge on one of its sides circumferentially extends 90° around the central finger rest area. In this arrangement the surfaces of the push buttons and the ridges completely cover an annular or ring region surrounding the central finger rest area.

In a preferred embodiment the input unit is arranged to be mounted on a centre console of a vehicle such that a pair of push buttons is disposed opposite to each other in a longitu ^¬ dinal direction of the vehicle, and a second pair of push but- tons is disposed opposite to each other in a direction perpendicular to the longitudinal direction of the vehicle. In this manner the driver has to move the finger tip of the index fin ^¬ ger forward or backward from the central finger rest area or laterally to the right or left hand side to reach a select one of the four push buttons.

In a preferred embodiment the push buttons and the central finger rest area are mounted on a mono-stable rotary knob mounted in the base to form an upper face of the rotary knob, wherein the axis of rotation of the rotary knob is perpendicu ^¬ lar to the upper surface of the basis. In this arrangement each individual push button can be depressed vertically with respect to the rotary knob, and the mono-stable rotary knob can be rotated with the push buttons as whole forth and back.

In a preferred embodiment the input unit is arranged to be mounted on a centre console of a vehicle such that the axis of rotation of the rotary knob is oriented vertically.

In an embodiment including a rotary knob it is preferred that the input unit is arranged to be mounted on a centre console of the vehicle such that a pair of push buttons is disposed opposite to each other in a longitudinal direction of the ve ^¬ hicle, and a second pair of push buttons is disposed opposite to each other in lateral direction perpendicular to the longitudinal direction of the vehicle when the mono-stable rotary knob is in the mono-stable position.

In a preferred embodiment utilizing a rotary knob the paddle shifter is connected to the rotary knob such that by moving the paddle shifter forth and back the rotary knob is rotated forth and back for manual shifting. In a preferred embodiment utilizing a rotary knob the rotary knob comprises a circular outer rim surrounding the push buttons, and the paddle shifter is connected to the rim of the rotary knob.

In a preferred embodiment the input unit is arranged to be mounted on a centre console of a vehicle such that the paddle shifter extends radially with respect to the central finger rest area and the annular arrangement of the push buttons and towards the driver seat.

In a preferred embodiment the input unit is arranged to be mounted on the centre console of the vehicle such that the paddle shifter extends perpendicular to the longitudinal di ^¬ rection of the vehicle when the mono-stable rotary knob is in the mono-stable position.

Such arrangements allow that the driver to place the finger tip of the index finger on the forwardly facing surface of the paddle shifter, and to place the thumb on the rearwardly fac ^¬ ing surface of the paddle shifter which allows easy operation of the paddle shifter for manual upshift and downshift by ro ^¬ tating the rotary knob forth and back with the paddle shifter grasped between index finger and thumb of the driver.

In a preferred embodiment the outer periphery of the annular push button arrangement is circular and has a diameter of less than 6 cm. In a preferred embodiment the central finger rest area is also circular and has a diameter of less than 2 cm.

A preferred embodiment of the invention will now be described with reference to the drawings in which: Fig. 1 shows a perspective view of a base of a shift-by-wire input unit arranged to be mounted on the centre console of a vehicle ;

Fig. 2 shows a perspective view of an upper portion of a rota ^¬ ry knob of the embodiment of Fig. 1 ;

Fig. 3 shows a front view of the base of the embodiment shown in the Figures (seen in direction opposite to the driving di ^¬ rection) ;

Fig. 4 shows a rear view of the base of the embodiment shown in the Figures (seen in driving direction) ;

Fig. 5 shows a top view of the preferred embodiment shown in the Figures;

Fig. 6 shows a cross-sectional view taken along the plane AA in Fig. 5; and

Fig. 7 shows a schematical perspective view of the embodiment illustrating the operation of the rotary know by driver.

Fig. 1 shows a perspective view of a base of a shift-by-wire input unit according to a preferred embodiment of the present invention. The base 20 of the shift-by-wire input unit is ar ^¬ ranged to be mounted in a centre console of a vehicle, wherein the base 20 is mounted in a recess of the centre console such that the upper surface 22 is flush with the surrounding upper surface of the centre console. In the preferred embodiment the upper surface 22 is, when the base 20 is mounted in the centre console, essentially oriented in a horizontal plane.

Four push buttons 2 (P, R, N and D) are arranged in an annular arrangement around a central finger rest area 8. The central finger rest area 8 and the surrounding push buttons 2 are mounted on a rotary knob 10 such that the upper surfaces of the push buttons 2 and of the central finger rest area 8 forms an upper face of the rotary knob 10. In Fig. 2 only an upper portion of the rotary knob is shown. The push buttons 2 are mounted on the rotary knob 10 such that they can be depressed with respect to the rotary knob 10 in a vertical direction in order to select any of the transmission states P, R, N or D.

The rotary knob 10 is rotatably mounted in the base 20 such that it can be rotated around a rotational axis which is ver ^¬ tically extending when the base 20 is mounted in a centre con ^¬ sole of a vehicle.

Two push buttons 2 of a pair of adjacent push buttons are sep ^¬ arated by a ridge 4 (in Figs. 1, 2 and 5 only one of the four ridges is provided with reference numeral 4) . The ridges ex ^¬ tend between adjacent two push buttons from the inner periphery of the push buttons adjacent to the central finger rest area 8 to an outer periphery of the push buttons 2. The ridges 4 are arranged such that they project from the upper surfaces of the neighboring push button surface areas. In this manner the ridges 4 form tangible separating elements. These separat ^¬ ing elements can provide a haptic perception to the driver that the finger tip of its index finger has reached the upper surface of a particular push button 2. If the driver feels a ridge at the finger tip this shows that the finger tip has been misplaced and is covering surface parts of adjacent push buttons 2 with the ridge 4 in-between. The ridges 4 also serve as guiding elements when the finger tip of the index finger of the driver is moving from the central rest area 8 to a partic ^¬ ular one of the push buttons 2.

The push buttons 2 are arranged such that, when the base 20 is mounted in a centre console of a vehicle, two push buttons of a pair of opposite push buttons are lying opposite to each other in longitudinal direction of the vehicle with the cen ^¬ tral finger rest area 8 in-between. The other two push buttons 2 are disposed opposite to each other in lateral direction with the central finger rest area 8 in-between. The driver first places the finger tip of the index finger on the central finger rest area 8. In this situation the central finger rest area 8 also serves as a reference location. When the finger tip of the index finger of the driver is placed in this refer ^¬ ence location the driver can reach any individual push button 2 by moving the finger tip forward, backward, to the left or to the right hand side. Then the selected push button 2 is pressed to select the desired transmission state, whereafter the finger tip of the index finger can return to the central finger rest area 8.

As can be seen in the perspective views of Figs. 1 and 2 the upper surfaces of the push button 2 and the central finger rest area 8 are shaped such that the upper surfaces of the push buttons 2 and the central finger rest area 8 form a gen ^¬ erally concave face. The upper surfaces of the push buttons 2 and the central finger rest area 8 are arranged such that they form a trough or hollow with respect to the surrounding upper surface 22 of the base 20. This arrangement provides a haptic perception for the driver that the finger tip has reached the central finger rest area 8 when the driver feels that the fin ^¬ ger tip has entered the hollow and has reached the surface portion at the lowest level which is formed by the central finger rest area 8. In this manner the central finger rest ar ^¬ ea 8 provides a haptic perception that the reference location has been reached by the finger tip, and that any of the push buttons 2 can be reached from this references location by mov ^¬ ing the finger tip forward, backward, to the left hand or to the right hand side. The cross-sectional view of Fig. 6 illustrates the mounting of the rotary knob 10 in the base 20. The push buttons 2 are in turn mounted in the rotary knob 10 to be vertically depressi- ble with respect to rotary knob 10. The rotary knob 10 com ^¬ prises an upper outer rim that is surrounding the outer periphery of the push buttons 2. To this upper rim of the rotary knob 10 a paddle shifter 12 is mounted and extends radially away from the outer rim of the rotary knob 10. The central finger rest area 8 can either rotate with the rotary knob 10 when the latter is rotated or can be stationary.

Fig. 7 illustrates how the driver can operate the rotary knob 10 of the shift-by-wire input unit. The driver puts his hand on the centre console of the vehicle such that the paddle shifter 12 can be grasped between the index finger and the thumb of the driver. In particular, the index finger is abutting the forwardly facing surface of the paddle shifter 12, and the thumb is abutting the surface of the paddle shifter 12 facing in rearward direction. In this manner the driver can perform manual upshift or downshift operations in a comforta ^¬ ble manner. More importantly, the driver can perform the manu ^¬ al upshift and downshift operations in a manner that is well distinguishable from the shift operations for selecting any of the transmission states P, R, N or D. This allows the driver to easily distinguish between the manual upshift and downshift operations on the one hand and the shift operations for se ^¬ lecting one of the transmission states P, R, N and D on the other hand in an intuitively clear manner which puts no extra cognitive load on the driver for performing the desired one of the operations.

In addition, the present invention allows to arrange the actu ^¬ ator for manual upshift and downshift operations and the push buttons for selection of transmission states in a very space saving manner next to each other. In addition, in the pre- ferred embodiment the actuator for manual upshift and down ^¬ shift and the push buttons for selection of transmission states are integrated into a single component, namely the ro ^¬ tary knob 10 in the base 20. This design is also advantageous in that only a single actuator component has to be provided and mounted in the base of the shift-by-wire input unit.