Motor vehicles – Manually actuated controlling devices – With transmission control
Reexamination Certificate
2002-07-11
2004-02-17
Carone, Michael J. (Department: 3616)
Motor vehicles
Manually actuated controlling devices
With transmission control
C180S315000, C074S473120
Reexamination Certificate
active
06691816
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to vehicle drive selector systems and more particularly to a golf car, forward-neutral-reverse drive selector system.
BACKGROUND OF THE INVENTION
In a simplistic form, there are three basic operating modes of a vehicle: forward, neutral and reverse. Traditionally, vehicles include a power plant, such as an internal combustion engine or an electric motor, or both, a transmission and a drive axle. The power plant supplies drive torque to the drive axle through the transmission, which provides gear reduction. A forward-neutral-reverse drive selector system (FNR system) is implemented to enable operator selection of the operating mode of the vehicle. For golf car applications, the FNR system is usually integrated into the drive, axle, which is then referred to as a transaxle.
FNR systems associated with golf car transaxles may use a pin, or dog-drive, system or a conventional automotive type synchronizer system to alternatively engage the drive axle for establishing forward or reverse. With particular regard to dog-drive systems, such FNR systems can only be engaged in discreet rotational positions, whereby the pins are aligned with receiving holes. If the pins are not properly aligned with the receiving holes, the drive axle must rotate further before forward or reverse modes may be properly established. These FNR systems are actuated through a rotary shaft protruding through a housing of the drive axle and include a minimal spring-loaded detent in the forward and reverse positions and optionally in the neutral position.
External to the drive axle, a cable operated FNR shift mechanism is provided for remote operation of the internal FNR system components. The FNR shift mechanism includes a rotary shift lever operating opposed, pull-type cables connected to the drive axle through a lever. Because the drive axle is unable to engage forward or reverse in any given rotational position, traditional FNR shift mechanisms also include a provision to enable the operator manipulated shift lever to shift fully into the forward or reverse position, while maintaining torque on the internal FNR system components.
This provision gives the operator tactile feedback that the shift is complete, although the actual shift may not complete until the pins align with the receiving holes. The provision includes a pair of compression springs which connect the cables of the FNR shift mechanism to the lever associated with the drive axle. When a cable is pulled, to select one of either forward or reverse, the cable compresses a spring until the spring force is sufficient to enable the drive axle to shift. If the shift pins are aligned with the receiving holes the shift occurs with minimal force. However, if the shift pins are out of alignment, the spring remains compressed and maintains torque on the drive axle shift mechanism until the pins become aligned. The operator manipulated shift lever goes over-center, using the force from the springs to maintain the shift. The compression springs remain under some load, transmitted through the cables, at all times that they are engaged.
Traditional FNR systems, like that described immediately above, retain specific disadvantages. Initially, because the shift cables are performing work to compress the springs, as opposed to shifting the drive axle, shifting effort is higher than desired. Also, wear on the cables is a concern because the cables are under load at all times. Further, because adjustment of the cable length determines the spring load during a shift event, the cable characteristics significantly influence feel and reliability. Finally, the over-centering of the FNR system occurring at the operator manipulated shift lever and the over-travel occurring at the drive axle shift lever makes it difficult to reliably locate the neutral position in the axle from the operator's location. For the same reasons, it is impractical to provide a neutral lock mechanism (for servicing and towing the vehicle) at an easily accessible location.
Therefore, it is desirable in the industry to provide an improved FNR system which overcomes the disadvantages associated with traditional FNR systems, as described in detail above.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a shift selector system for selecting an operating mode of a vehicle axle. The shift selector system includes an operator shift mechanism and an axle shift mechanism. The operator shift mechanism has a rotatably supported cam rotatable between a forward position, a neutral position and a reverse position and a spring operably interconnected to the cam for selectively biasing the cam toward one of the forward position and the reverse position such that an axis of the spring selectively intersects a rotational axis of the cam when the cam is in the neutral position, whereby the spring is ineffective for rotationally biasing the cam and is effective for rotationally biasing the cam when the cam is in one of the forward or neutral positions. The axle shift mechanism is operably interconnected to the vehicle axle and is in remote communication with the operator shift mechanism. The axle shift mechanism includes a shift lever respectively rotatable with rotation of the cam for establishing the operating mode of the vehicle axle.
The present invention also provides a compression spring assembly associated with the axle shift mechanism for enabling delayed rotation of the shift lever to a respective position induced by rotation of the cam. In this manner, mode shifting can occur once the internal components of the drive axle are properly aligned and stress in the push/pull cable can be relieved.
The present invention further provides a neutral lock mechanism operably supported by the cam for selectively prohibiting rotation of the cam from the neutral position. In this manner, the neutral lock mechanism is easily accessible by an operator and enables locking of the drive axle in the neutral mode for maintenance or towing purposes.
Additionally, the present invention provides a notification system operably interconnected with the operator shift mechanism for providing a notification when the cam is in the reverse position. The notification system includes a switch in operable communication with the cam, whereby the switch is actuated as a function of a rotational position of the cam, and a notification buzzer in electrical communication with the switch for providing the notification upon actuation of the switch.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
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Carone Michael J.
Harness & Dickey & Pierce P.L.C.
Textron Inc.
Thomson M.
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