Shift lever assembly for power transmission of automotive vehicle

A shift lever assembly composed of a tubular lever member mounted at its lower end on a stationary support block to be shifted in a fore-and-aft direction, an operation rod slidably disposed within an axial bore of the lever member and provided at its lower end with a detent mechanism for retaining the lever member in a shifted position, and an operation knob having a grip portion connected to the upper end of the lever member and an operation button assembled with the grip portion, wherein the grip portion is formed with a cavity which opens in one direction and contains the upper end of the operation rod, and the operation button is rotatably assembled within the cavity of the grip portion to be moved downward along a semi-circular path by operation of the operator, the operation button having a projection formed therewith for engagement with the upper end of the operation rod and being biased upward by a spring assembled within the cavity of the grip portion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a shift lever assembly adapted for use in 
a power transmission of an automotive vehicle. 
2. Description of the Prior Art 
As disclosed in Japanese Utility Model Publication Nos. 62-162719 and 
63-49764, a conventional shift lever assembly for a power transmission is 
composed of a tubular lever member rotatably mounted at its lower end on a 
support block secured to a vehicle body structure to be moved in a 
fore-and aft direction and connected to a shift arm of the power 
transmission by means of a connecting linkage, an operation knob connected 
to the upper end of the tubular lever member, a detent mechanism provided 
within an internal bore of the lever member to releasably restrict 
movement of the lever member with respect to the support block. When the 
detent mechanism is released by operation of the operation knob, the level 
member can be moved forwardly or backwardly to shift the power 
transmission. 
The operation knob has a grip portion connected to the upper end of the 
lever member, the grip portion being formed therein with a lateral cavity 
opening outwardly at one side thereof and containing the upper end of an 
operation rod of the detent mechanism therein, an operation button 
slidably disposed within the lateral cavity of the grip portion, the 
operation button being exposed outwardly at its one end and engaged with 
the upper end of the operation rod at its other end, and a spring 
assembled within the lateral cavity to bias the operation button 
outwardly. In operation of the operation knob, the operation button is 
pushed inwardly against the biasing force of the spring to move the 
operation rod downward. Thus, the detent mechanism is released by downward 
movement of the operation rod to permit forward or backward movement of 
the lever member. 
In the operation knob, the engagement portion of the operation button with 
the upper end of the operation rod is formed with an inclined cam surface 
on which the operation effort applied to the button in the lateral 
direction is converted into a downward force for movement of the operation 
rod. Accordingly, lateral movement of the operation button causes sliding 
movement of the inclined cam surface relative to the upper end of the 
operation rod. This results in an increase of the load acting on the 
operation button. Although the operation button is slidably assembled 
within the grip portion, it is difficult to provide the operation button 
with sufficient sliding surfaces in the grip portion. This results in 
unwanted movements of the operation button in operation. 
SUMMARY OF THE INVENTION 
It is, therefore, a primary object of the present invention to provide an 
improved shift lever assembly capable of minimizing the load acting on the 
operation button without causing unwanted movements of the operation 
button in operation. 
According to the present invention, the object is attained by providing a 
shift lever assembly adapted for use in a power transmission of an 
automotive vehicle, which comprises a tubular lever member formed therein 
with an axial bore and mounted at its lower end on a stationary support 
block secured to a vehicle body structure to be shifted in a fore-and-aft 
direction; an operation rod slidably disposed within the axial bore of the 
tubular lever member and provided at its lower end with a detent mechanism 
for retaining the lever member in a shifted position, and an operation 
knob having a grip portion connected to the upper end of the tubular lever 
member and an operation button assembled with the grip portion and 
maintained in engagement with the upper end of the operation rod to 
release the detent mechanism when operated by an operator; wherein the 
grip portion of the operation knob is formed with a cavity which opens in 
one direction and contains the upper end of the operation rod, the 
operation button of the operation knob is rotatably assembled within the 
cavity of the grip portion to be moved downward along a semi-circular path 
by operation of the operator, the operation button being formed with a 
projection for engagement with the upper end of the operation rod, and 
resilient means is assembled within the cavity of the grip portion to bias 
the operation button upward for engagement with an upper end of the cavity 
.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, FIG. 1 illustrates a change-speed operation 
mechanism which is mounted on a support block 22 secured to a vehicle body 
structure (not shown) and operatively connected to an automatic power 
transmission (not shown). As shown in FIGS. 1 and 2, the change-speed 
operation mechanism includes a shift lever assembly composed of a lever 
member 10a, an operation knob 10b, a first detent mechanism 10c and a 
second detent mechanism 10d. The lever member 10a is in the form of a 
tubular lever member 11a integrally formed at its lower end with a support 
portion 11b perpendicularly thereto and a connecting arm 11c extending 
forwardly from its lower end portion. The operation knob 10b is assembled 
with the upper end of tubular lever member 11a by means of a joint means 
12. The first detent mechanism 10c is disposed within an axial bore of the 
tubular lever member 11a, and the second detent mechanism 10d is assembled 
with the lower end of the tubular lever member 11a at one side thereof. As 
shown in FIG. 2, a lateral support shaft 21 is coupled within an axial 
bore of the support portion 11b and carried on mutually opposed upstanding 
portions of the support block 22 so that the tubular lever member 11a is 
arranged to be shifted forwardly or backwardly. In a condition where the 
tubular lever member 11a has been assembled with the support block 22 as 
described above, the connecting arm 11c of lever member 11a is connected 
at its distal end to one end of an inner wire 23 of an operation cable as 
shown in FIG. 1, and the other end of inner wire 23 is connected to a 
shift arm (not shown) of the automatic power transmission. 
As clearly shown in FIG. 2, the first detent mechanism 10c includes an 
operation rod 13a, a lateral engagement pin 13b and a compression coil 
spring 13c, The operation rod 13a is slidably disposed within the axial 
bore of tubular lever member 11a. The engagement pin 13b is fixed to the 
lower end of operation rod 13a perpendicularly thereto and extends 
outwardly at its opposite ends through a pair of elongated holes formed in 
the peripheral wall of tubular lever member 11a. The compression coil 
spring 13c is disposed within the axial bore of tubular lever member 11a 
to bias the operation rod 13a upwardly. In such an arrangement of the 
first detent mechanism 10c, the engagement pin 13b is loaded upward by the 
compression coil spring 13c and engaged at its right-hand end with one of 
plural recesses 22b formed on the right-hand upstanding portion 22a of 
support block 22 to restrict the forward or backward movement of the 
tubular lever member 11a. 
As clearly shown in FIG. 2, the second detent mechanism 10d includes a 
compression coil spring 14a disposed within an additional axial bore 
formed in an enlarged lower end of tubular lever member 11a and a detent 
ball 14b carried by the compression coil spring 14a. The detent ball 14b 
is maintained in engagement with one of plural recesses formed on the 
left-hand upstanding portion 22c of support block 22. In the second detent 
mechanism 10d, the detent ball 14b passes over the recess engaged 
therewith in forward or backward movement of the shift lever assembly and 
is successively engaged with other recesses of the left-hand upstanding 
portion 22c under the load of compression coil spring 14a. This is 
effective to apply an operatinal feel to the operator in shifting 
operation of the shift lever assembly and to retain the shift lever 
assembly in its shifted position. 
As shown in FIGS. 3 and 4, the operation knob 10b has a grip portion 15, an 
operation button 16 rotatably assembled within the grip portion 15 and 
exposed outwardly at its upper part and a torsion spring 17 assembled 
within the grip portion 15. The grip portion 15 and operation button 16 
are respectively composed of an internal layer portion 15a, 16a of hard 
synthetic resin and an external layer portion 15b, 16b of soft synthetic 
resin. The grip portion 15 is formed with a cavity opening upwardly. The 
internal layer portion 15a of hard synthetic resin is formed with an axial 
bore 15c extending downwardly and a recess 15d located in parallel with 
the axial bore 15c. As shown in FIGS. 4 and 5, the internal layer portion 
15a of grip portion 15 is formed at its opposite side walls with a pair of 
spaced support pins 15e which are arranged along a semi-circular path and 
project inwardly at the upper portion of the cavity in grip portion 15. In 
a condition where the grip portion 15 has been connected to the upper end 
of tubular lever member 11a, the operation rod 13a of detent mechanism 10c 
extends into the cavity of grip portion 15 through the axial bore 15c of 
internal layer portion 15a. 
The internal layer portion 16a of operation button 16 is formed with first 
and second projections 16c, 16d which extend downwardly in the cavity of 
grip portion 15, and the external layer portion 16b of operation button 16 
is formed to cover the cavity of grip portion 15. As shown in FIG. 6, the 
internal layer portion 16a of operation button 16 is formed at its 
opposite sides with a pair of semi-circular grooves 16e for engagement 
with the spaced support pins 15e of grip portion 15. The operation button 
16 is coupled with the upper opening trim of grip portion 15 so that the 
semi-circular grooves 16e of button 16 are engaged with the support pins 
15e of grip portion 15. In such a condition, the operation button 16 is 
slidably supported by the support pins 15e of grip portion 15 to be 
movable along the semi-circular grooves 16e and is engaged at its upper 
end with the upper edge of grip portions 15. Thus, upward movement of the 
button 16 is restricted by engagement with the upper edge of grip portion 
15, and downward movement of the button 16 is restricted by engagement 
with the upper support pins 15e. 
As shown in FIG. 3, a torsion spring 17 is formed with a coiled portion 17a 
and a pair of legs 17b, 17c. The coiled portion 17a of spring 17 is 
contained within the internal recessed portion 15d of grip portion 15 in 
such a manner that the spring 17 is engaged at its one leg 17b with a side 
face of the second projection 16d of button 16 and at its other leg 17c 
with a groove 15f formed in the peripheral wall of grip portion 15. Thus, 
the operation button 16 is retained in an upward position by the biasing 
force of spring 17 to cover the cavity of grip portion 15 and is engaged 
at its first projection 16c with the upper end of operation rod 13a. 
When the grip portion 15 has been grasped by an operator's hand for use of 
the operation knob 10b, the operation button 16 can be operated by the 
thumb of his hand against the biasing force of the spring 17 to push down 
the head of operation rod 13a at its first projection 16c. Thus, the first 
detent mechanism 10c is released by downward movement of the operation rod 
13a to permit forward or backward movement of the shift lever assembly for 
shifting the power transmission. In such operation of the operation knob 
10b, the operation button 16 is rotated along the semi-circular path to 
cause the downward movement of operation rod 13a. Thus, the operation 
effort applied to the button 16 is directly transmitted to the operation 
rod 13a. This is useful to decrease the load acting on the operation 
button 16. Since the operation button 16 is assembled with the grip 
portion 15 by means of engagement with the support pins 15e of grip 
portion 15 at its semi-circular grooves 16e, the sliding portion of 
operation button 16 can be prolonged to minimize unwanted movements of the 
operation button 16 so as to enhance operational feel of the operation 
button 16. 
In FIGS. 7 and 8, there is illustrated another embodiment of the present 
invention, wherein an operation knob 30b is composed of a grip portion 35, 
an operation button 36, a torsion spring 37 and a cover member 38. The 
grip portion 35 is composed of an internal layer portion 35a of hard 
synthetic resin and an external layer portion 35b of soft synthetic resin. 
The operation button 36 and cover member 38 each are made of hard 
synthetic resin. As shown in FIGS. 7-9, the grip portion 35 is formed 
therein with a cavity opening in a lateral direction. The internal layer 
portion 35a of grip portion 35 is formed with an axial bore 35c extending 
in a vertical direction and a pair of laterally spaced support holes 35d 
which are located at a bottom portion of the cavity in grip portion 35 as 
shown in FIG. 8. The internal layer portion 35a of grip portion 35 is 
further formed with a projection 35e which is composed of hard and soft 
synthetic resin layers and is opposed to the axial bore 35c. In a 
condition where the grip portion 35 has been connected to the upper end of 
a lever member 30a and a tubular lever member 31 by means of a joint means 
32, an operation rod 33a of a detent mechanism (not shown) is extended 
into the cavity of grip portion 35 through the axial bore 35c of internal 
layer portion 35a. 
As shown in FIGS. 10 and 11, the operation button 36 is formed with a body 
portion 36a, a pair of legs 36b and a projection 36c and is further formed 
with support holes 36d at the lower ends of its legs 36b. As shown in FIG. 
7, the operation button 36 is assembled within the cavity of grip portion 
35 in such a manner that the body portion 36a is exposed outwardly through 
a portion of the cover member 38 which is coupled with the opening of the 
cavity of grip portion 35. The operation button 36 is rotatably carried by 
a support pin 39 which is inserted into the support holes 36d of legs 36b 
and engaged at its opposite ends with the support holes 35d of grip 
portion 35. The cover member 38 is formed at its internal wall with a 
projection 38a which is coupled with the support pin 39 of operation 
button 36 to retain the cover member 38 in place. 
The torsion spring 37 is formed with a coiled portion and a pair of legs in 
the same manner of the torsion spring 17 shown in FIG. 3. The coiled 
portion of spring 37 is arranged in surrounding relationship with the 
support pin 39 of operation button 36 so that the spring 37 is engaged at 
its one leg with a bottom of the cavity of grip portion 35 and at its 
other leg with one of the legs 36b of operation button 36. In such an 
arrangement of the torsion spring 37, the projection 36c of operation 
button 36 is resiliently engaged at its upper end with the internal 
projection 35e of grip portion 35 under the biasing force of spring 37 and 
is engaged at its lower end with the upper end of operation rod 33a. 
When the grip portion 35 has been grasped by an operator's hand, the body 
portion 36a of operation button 36 can be rotated inwardly by the thumb of 
his hand against the biasing force of spring 37 to push down the operation 
rod 33a at its projection 36c. Thus, the detent mechanism is released by 
downward movement of the operation rod 33a to permit forward or backward 
movement of the shift lever assembly for shifting the power transmission. 
In such operation of the operation knob 30b, the operation button 36 is 
rotated along a semi-circular path to cause the downward movement of 
operation rod 33a. Thus, the operation effort applied to the button 36 is 
directly transmitted to the operation rod 33a. This is useful to minimize 
the load acting on the operation button 36 so as to enhance operational 
feel of the operation button 36.