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US 6,645,112 B1Granted
On-demand transfer case
AssigneeNew Venture Gear, Inc.
InventorsYakov Fleytman, Carl D. Schleuder
Life of this patent
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AssigneeNew Venture Gear, Inc.
InventorsYakov Fleytman, Carl D. Schleuder
Estimating the term…
A torque transfer system is disclosed which is particularly well-suited for use in four-wheel drive transfer cases to establish distinct two-wheel and four-wheel drive modes as well as providing an automatic (“on-demand”) four-wheel drive mode. The torque through system includes a planetary gearset having a first component driven by an input member, a second component driving an output member, and a third component driven by a worm gearset. The worm gearset includes a worm gear fixed for rotation with the third component and a worm meshed with the worm gear. A variable speed motor drives the worm for varying the speed ratio between the first and third components of the planetary gearset, thereby causing a corresponding variation in the drive torque transferred from the input member to the output member.
A transfer case for use in a four-wheel drive vehicle having a powertrain and first and second drivelines, comprising:
A transfer case for use in a four-wheel drive vehicle having a powertrain and first and second drivelines, comprising:
A transfer case for use in a four-wheel drive vehicle having a powertrain and first and second drivelines, comprising:
A transfer case for use in a four-wheel drive vehicle having a powertrain and first and second drivelines, comprising:
The transfer case of 13 further comprising a mode selector for permitting selection of said locked four-wheel drive mode and said on-demand four-wheel drive mode, said mode selector operable for sending a mode signal indicative of the specific drive mode selected to said controller, whereby said motor is non-actuated and said worm gearset is held stationary when said locked four-wheel drive mode is selected, and whereby said motor is variably actuated in response to said sensor signals to vary the rotary speed of said carrier relative to said first output shaft for varying the torque transmitted to said second output shaft when said on-demand four-wheel drive mode is selected.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
For changing number of driven wheels , for switching from driving one axle to driving two or more axles: for varying torque distribution between…
The transfer gear being a differential gear: with means for changing distribution of torque between front and rear wheels
With a secondary drive, e.g. regulating motor, in order to vary speed continuously: using externally powered electric machines
Worm: variable speed
Term ended 12 Oct 2020 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates generally to transfer cases for use in four-wheel drive vehicles and, more particularly, to a variable ratio torque transfer coupling for transfer cases.
In general, power transfer mechanisms, such as transfer cases, are operatively associated with both manual and automatic transmissions for directing power to the non-driven wheels of a motor vehicle for establishing a four-wheel drive mode. Many automotive transfer cases are now equipped with a torque transfer assembly that is capable of automatically shifting (“on-demand”) between the two-wheel drive mode and the four-wheel drive mode. Examples of on-demand transfer cases incorporating torque transfer coupling are shown in U.S. Pat. Nos. 5,215,160; 5,443,426; 5,400,866; 5,597,369; 6,041,903; and 6,112,874. While such on-demand transfer cases have proven to provide enhanced traction control compared to traditional part-time transfer cases, the need exists for continued development of improved torque transfer systems.
In view of the foregoing, it is an object of the present invention to provide a unique torque transfer system for use in vehicular power transfer assemblies which can continuously vary the torque transferred from an input member to an output member;
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a sectional view of a worm/worm gear transmission with the worm gear having three teeth according to the principles of the present invention;
FIGS. 2 and 3 are views of a worm/worm gear transmission with the worm gear having six teeth according to the principles of the present invention;
In general, the present invention relates to a variable torque transfer system which is capable of functioning at any point in the continuum of torque levels between a no-torque operating state and a high-torque operating state. Thus, the present invention is adapted for use in virtually any transfer case of a four-wheel drive vehicle for permitting selective shifting or automatic variable control between a two-wheel drive mode (2WD) and a locked four-wheel drive mode (4WD-LOCK) and at any point in the torque range therebetween. The variable torque transfer system for use in transfer cases according to the principles of the present invention will be described below with reference to FIGS. 24 through 27. However, the following discussion relating to FIGS. 1-23 provides a detailed description and several examples of the unique enveloping-type worm/worm gear transmissions which can be utilized with the variable range system of the present invention.
The reason for using an enveloping-type worm gear is that this type of worm gear has a natural profile of tooth surface which is distinct from other types of thread followers. The configuration of the worm gear teeth is generated by the profile of the thread or threads of the worm. A computer model simulation is utilized to generated the configuration of the worm gear teeth of the worm gear. The worm gear is then formed using known techniques such as hobbing or casting. When the worm gear teeth are generated by the profile of the threads of the worm having different lengths for the same enveloping angle (shortened), the profiles of the worm teeth is different. The main advantage for using the enveloping-type worm gears is more torque capacity.
The worm thread has a rolling action contract relationship with the teeth of the worm gear which provides an increased efficiency. Furthermore, it is beneficial to have the pitch diameter in the center of the worm gear. With standard worm designs, with more than one thread and a large enveloping angle, the inability to assemble the worm and worm gear was considered a major obstacle. With the worm and worm gear of the present invention, the worm and worm gear are easily assembled by properly orienting the worm thread and worm teeth.