Japan

Clutch for Parking Lock system

  • Roller ratchet clutch

This mechanism locks the rotation inside the transmission or e-Axle, so the wheels do not rotate when the shift lever of automatic and xEV vehicles is set to park.
Below, we propose a unique system using a roller ratchet clutch.

Leaflet

Clutch for Parking Lock system

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Workings

The main components consist of an inner ring, outer ring, selector, roller, and spring. The clutch roller position is controlled by the selector to switch between the free mode and the lock mode.
Operated by a combination of an actuator and a rod, this mechanism realizes simple mode switching: free (OFF) when driving, and locked (ON) when parked.

Features

Functions specific to parking locks integrated into a compact clutch unit

  • Lock standby mode

    A spring built into the rod also provides a lock standby mechanism to allow switching even when only half-engaged.

  • Starting from lock mode

    The rollers between the inner and outer wheels are angled so that the rollers are released when the selector is released, even under heavy load conditions on slopes, etc., for smooth switching.

  • Malfunction prevention

    The inner ring chamfer provides a safety feature that prevents sudden locking due to malfunction where the roller is bounced.

  • Low drag torque

    By securing a gap between the inner and outer rings, the roller and inner ring are not in contact with each other when traveling, resulting in low drag torque.

  • Low backlash and secure locking when stopped

    The selector locks roller pop-out and is not released by input from the tires.

Reduction in the Number of Parts and Compactness by Unitization of the Clutch Mechanism

Reduction in the number of parts and assembly man-hours = 70% reduction in unit parts. (Based on our own research)

Compact and lightweight mechanism = 25% reduction in area dedicated to the parking lock. (Based on our own research)

Up to to 25% downsizing

Reduction in processing cost of case body = 75% reduction in processing areas. (Based on our own research)

Detent mechanismNEW

Parking lock clutch with a detent mechanism

This is an optional solution that integrates the detent (position-holding) function required for the parking lock mechanism directly into the clutch unit.
By eliminating the actuator’s position-holding mechanism, it helps achieve a more compact design and lower overall costs.

Workings

The free-to-lock mechanism operates on the same principle as a standard parking lock clutch.
Even if the actuator is de-energized while in the lock standby state, the locked or lock-standby condition can be maintained by the detent spring and the serrated profile of the flange.

Tsubaki offers the option to select whether or not a detent mechanism is included.

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Mobility

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