Hybrid Vehicle Clutch Control for Engine Start Shock Suppression

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Solution Overview

Problem

Conventional hybrid vehicle control devices fail to effectively suppress engine start shock during coasting/regenerating driving, making it difficult to provide initial information acceleration when increasing driving force, as they rely on reducing motor rotational speed by changing transmission ratios.

Innovation Solution

A hybrid vehicle control device with a first clutch between the engine and motor/generator, and a second clutch between the motor/generator and drive wheels, uses the motor/generator for engine start by completely disengaging the second clutch and allowing the first clutch to slip engage, facilitating engine cranking and ignition, thereby preventing torque fluctuations and shock transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the transmission ratio is changed to the high side to reduce motor rotational speed for engine start, then engine start shock is suppressed, but initial information acceleration sensation cannot be provided when increasing driving force

Engineering Contradiction:

Improveengine start shockVSAvoidinitial information acceleration

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The patent divides the clutch control into two independent stages: first completely disengaging the second clutch to isolate the drive wheels from torque fluctuations, then engaging the first clutch to transmit engine torque. This segmentation allows independent optimization of shock suppression and acceleration response.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second clutch is completely disengaged before engine start occurs, preparing the system in advance to prevent torque transmission. This preliminary action ensures that when the engine starts, no shock is transmitted to the drive wheels, while simultaneously enabling immediate torque transmission capability.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the transmission ratio is changed to the high side to reduce motor rotational speed, then engine start is enabled, but clutch durability deteriorates due to rotational speed fluctuations

Engineering Contradiction:

Improveengine start capabilityVSAvoidclutch durability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The second clutch is completely disengaged before engine start, preparing the system in advance to prevent torque transmission. This preliminary action ensures that when the engine starts, no shock is transmitted to the drive wheels, while simultaneously enabling immediate torque transmission capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The clutch control is divided into two independent stages: first disengaging the second clutch to isolate the drive wheels, then engaging the first clutch to transmit engine torque. This segmentation protects the clutch from rotational speed fluctuations during engine start.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If the second clutch is completely disengaged during engine start, then torque fluctuation is prevented from transmitting to drive wheels, but regenerative torque and coast deceleration are released

Engineering Contradiction:

Improvetorque fluctuation transmissionVSAvoidregenerative torque

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent converts the harmful effect of complete disengagement (loss of regenerative torque) into a benefit by timing the disengagement specifically during engine start when shock suppression is critical. The regenerative torque is temporarily sacrificed to prevent engine start shock, but this is acceptable since it occurs only during the brief engine start period.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP3056369B1Device for controlling hybrid vehicle

Publication Date: 2018.09.19 NISSAN MOTOR CO LTD

Figure 1
Figure 2
Figure 3

AI summary

To provide a hybrid vehicle control device that can cause the sensation of an initial information acceleration with respect to an increase in the required driving force, while suppressing engine start shock during engine start during coasting/regenerating driving. An engine start control means (Figure 2), which performs engine start control with a motor/generator (4) as an engine starting motor when an engine starting request has been generated on the basis of an increase in required driving force during coasting/regenerating driving by the motor/generator (4) in an EV mode during which traveling is performed by disengaging a first clutch (3) and engaging a second clutch (5), is configured having: a second clutch control section that completely disengages the second clutch (5); and an engine start control section that engages or causes the slip engagement of the first clutch (3), and performs engine start control resulting from performing an engine cranking operation, injecting air and fuel, and igniting same.