Machine element or mechanism – Control lever and linkage systems – Elements
Reexamination Certificate
1999-03-29
2001-04-24
Fenstermacher, David (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Elements
C074S531000
Reexamination Certificate
active
06220114
ABSTRACT:
TECHNICAL FIELD
The present invention relates to control device subassemblies and, in particular, to an automotive HVAC control device having tactile feedback.
BACKGROUND OF THE INVENTION
Operation controls for heating ventilation and air conditioning (HVAC) systems in automobiles often provide tactile feedback to the operator. The feedback represents finite incremental changes or gradients as, for example, the temperature control knob is rotated clockwise from “cold” to “hot.” In some applications, instead of a knob, a sliding scale is used which, for example, when moved from left to right provides tactile feedback of finite incremental changes from “cold” to “hot.” One common method of providing this tactile, mechanical, feedback is to move a spring steel or plastic ball across a series of detents.
Referring to
FIG. 1
, there is shown one embodiment of providing tactile feedback in an HVAC detent application. The assembly includes a ball
10
positioned atop a coil spring
14
. The ball
10
is held into place by grease
12
or a similar tacky substance such that the stainless steel ball adheres to the spring during handling. The other end of the coil spring is attached, directly or indirectly, to a control knob or sliding indicator. In operation, the ball
10
, which can be steel or plastic, will tend to engage a detent
15
due to the biasing force of the spring
14
. As the knob is rotated, or slider moved laterally, the ball
10
will engage in each detent
15
with which it axially aligns, thereby providing tactile feedback as each detent
15
contacts the ball
10
. The ball, spring, and detent also act to maintain the position of the control indicator.
The prior art ball and spring assembly of
FIG. 1
has several drawbacks when used for HVAC system detent applications, however. In particular, the ball and spring can become easily separated when handled or in operation. In addition, the grease required to hold the ball to the spring collects dirt which can reduce the wear characteristics of the ball, particularly in the case of a plastic ball. The grease also has a tendency to contaminate other components of the system and the assembly environment in general. The difficulty in handling the separate ball, spring, and grease assembly also increases the overall assembly costs.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a solution to the above mentioned problems.
According to the present invention, the foregoing and other objects and advantages are attained by a control device having tactile feedback which includes an elongated tubular bullet housing and a coil spring slidably engaged in said housing. The housing includes a semi-spherical cap enclosing one end. The cap is biased by the coil spring against a scale having a plurality of detents which represents gradients along the scale. The coil spring provides a biasing force such that, during relative movement between the housing and the scale, the end cap disengages each detent as it moves away and engages each detent as it becomes axially aligned with said housing.
In another embodiment, the housing includes an interior notch such that upon insertion of the coil spring into the housing, the coil spring and housing engage so as to prevent the separation of the coil spring and housing during handling of the assembly.
One advantage of the present invention is the reduced likelihood that the housing and spring separate during handling or operation as compared to the prior art spring and ball assembly.
Another advantage is reduced costs and easier assembly handling because the lack of grease as compared to the prior art spring and ball assembly.
REFERENCES:
patent: 3986410 (1976-10-01), Robinson
patent: 4681202 (1987-07-01), Dinse
patent: 4807489 (1989-02-01), Schreiner et al.
patent: 5020389 (1991-06-01), Sigler
Delphi Technologies Inc.
Fenstermacher David
Funke Jimmy L.
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