Machine element or mechanism – Control lever and linkage systems – Foot operated
Reexamination Certificate
1999-08-26
2001-04-03
Lorence, Richard M. (Department: 3681)
Machine element or mechanism
Control lever and linkage systems
Foot operated
C074S560000, C074S514000, C123S399000
Reexamination Certificate
active
06209418
ABSTRACT:
TECHNICAL FIELD
The subject invention relates generally to electronic throttle control device for a vehicle pedal assembly. Specifically, the electronic throttle control includes a resilient member interacting between the housing and a pedal portion to generate a kickdown feel of a vehicle downshift at the pedal pad.
BACKGROUND OF THE INVENTION
The invention relates to foot pedal devices for controlling engines without the need for a direct mechanical connection between the pedals and the engines. The invention is particularly directed to providing a drive-by-wire system, i.e., driving by electrical or electronic means, rather than by mechanical links.
In the prior art, accelerator pedals are used to mechanically control a vehicle engine and usually include a pedal mounted to a vehicle body with a series of links and levers, or Bowden cables, connecting the pedal to the carburetor, fuel injector, controller, or other similar device. These linkages must be designed to withstand and accommodate engine movements relative to the vehicle frame, as well as to provide accurate control despite such movements. In addition, packaging space must be provided for the linkages to function properly. The space available for routing the mechanical control links, rods, and cables is limited. When electrical sensors are used to monitor the position of the pedal, connection to the carburetor or other engine device can be accomplished with electrical wiring, which is more easily routed through the vehicle.
In drive-by-wire applications, it is important that the pedal system provide the customary feel and performance of a mechanical linkage. The pedals must function responsively to driver input and must provide non-fatiguing resistance. Drivers are accustomed to applying and releasing pressure on a pedal arrangement and become accustomed to the resistance to application of force to the pedal as well as to the rate of withdrawal as the applied pressure is relaxed. With the present invention, the customary feel during the application of force to increase speed and while maintaining speed, as well as the familiar deceleration movement of the pedal can be duplicated in a wire type control.
The accelerator pedal is connected to a potentiometer or other sensor that is used to monitor the position of the pedal with respect to a reference point. The potentiometer generates a signal that varies in magnitude with respect to the pivotal position of the accelerator pedal. This signal is sent to a computer processor that is wired to the potentiometer. The processor uses the sensor signal along with various other parameters to generate a control signal for controlling the position of the engine throttle through a wire connection.
The accelerator pedal is operable between an idle position and a maximum travel position. When a force is applied to the pedal, the pedal pivots to an operating position somewhere between the idle and maximum travel positions. Sometimes the driver will desire a fast acceleration, which will cause the automatic transmission to change to a next lower gear. In a mechanical linkage, when the transmission makes this downshift, a certain feel is imparted to the driver's foot via the pedal assembly. This feel is referred to as kickdown. An example of a kickdown mechanism that is used to initiate a transmission downshift for a pedal that is mechanically linked to an engine throttle is shown in U.S. Pat. No. 5,697,253. With the present invention, the customary feel during the downshift can be duplicated in a wire type control such that the driver can feel the kickdown at the pedal.
An example of an electrical kickdown switch used in an electronic throttle control pedal assembly to initiate a transmission downshift is shown in U.S. Pat. No. 5,806,376. However, these electronic control pedal assemblies do not include a mechanical mechanism for imparting the kickdown feel to a driver. The present invention provides an electronic throttle control pedal assembly with a kickdown generating mechanism that imparts a transmission shift feel to the driver. The kickdown generating mechanism requires few components, is easy to maintain, and is easily assembled into an electronic throttle control pedal.
SUMMARY OF THE INVENTION AND ADVANTAGES
An accelerator pedal assembly for electronically controlling a vehicle engine throttle includes a housing for attachment to a vehicle structure and a pedal arm with an upper end pivotally supported with respect to the housing and a lower end for supporting a pedal pad. The pedal arm is pivotable between a plurality of operable positions as a pedal force is applied to the pedal pad. The pedal arm presents a cam surface for interacting with a resilient member that has a first end fixed relative to the pedal arm and a movable second end for bias engagement with the pedal arm. The resilient member is forced into contact with a portion of the cam surface when the pedal arm is pivoted from a first operable position to a predetermined second operable position such that the pedal force required to further pivot the pedal arm is increased.
The vehicle engine is operably connected to a transmission that is shiftable between a plurality of high and low gear positions as the pedal arm is pivoted between operable positions. Preferably, the second operable position is defined as a kickdown position where the transmission shifts from a high gear position to a low gear position under certain pre-defined conditions. In the preferred embodiment, the pedal arm is pivoted from an idle position to the first operable position when a first pedal force is applied to the pedal pad; the pedal arm is pivoted from the first operable position to the kickdown position when a second pedal force is applied to the pad; and the pedal arm is pivoted from the kickdown position to a maximum applied position when a third pedal force is applied to the pedal pad. The second pedal force is greater than the first or third pedal force, which imparts a downshift feel to a driver via the pedal pad. It should also be understood that the pedal could be configured to only require two pedal forces as compared to three pedal forces.
Also in the preferred embodiment, the resilient member is comprised of a spring having one end seated within the housing and an opposite end connected to a roller for engaging the cam surface as the pedal arm is moved from an idle position to a maximum applied position. The cam surface is preferably comprised of a first portion, a central portion having a lobe extending outwardly from the surface, and a second portion. The roller engages the first portion when the pedal arm is pivoted from the idle position to the first operable position, engages the lobe when the pedal arm is in the kickdown position, and engages the second portion when the pedal arm is pivoted from the kickdown position to the maximum applied position. Thus, the second pedal force is increased as the roller is forced over the lobe to simulate a transmission shift feel at the pedal pad as the transmission shifts from a high gear position to a low gear position.
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Kalsi Avtar S.
Wheeler Douglas J.
Howard & Howard
Lorence Richard M.
Teleflex Incorporated
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