Vehicle Control Device Suppressing Engagement Shock
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Solution Overview
Problem
Existing vehicle control systems experience engagement shock during state switching of engagement devices in an engine rotation stop state, particularly when switching between differential rotation speeds, which affects drivability and increases the likelihood of engagement shock.
Innovation Solution
A control device that includes engagement control and differential rotation suppression control portions to manage the operational states of engagement devices, ensuring the differential rotation speed is reduced to a predetermined value before state switching, and the engagement devices are only engaged after synchronization, thereby minimizing engagement shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engagement device is switched to a different engaged state during engine rotation stop, then the power transmission ratio can be changed, but the differential rotation speed becomes large causing engagement shock
Solution Approach 1:
The control device starts the engine before switching the engagement device to a new engaged state. This preliminary action allows the differential rotation speed to be reduced gradually during engine startup, preventing large differential rotation speeds at the moment of engagement switching and thereby suppressing engagement shock.
Solution Approach 2:
The control device applies preliminary anti-action by controlling the engine startup process to counteract the tendency toward large differential rotation speeds. The engine is started and its rotation speed is controlled to reduce the differential rotation speed between engagement elements before the engagement device is switched, thus preventing engagement shock in advance.
2Ease of operation
If the engagement device is switched while maintaining engine rotation stop, then the switching operation is simple, but the differential rotation speed cannot be controlled leading to engagement shock
Solution Approach 1:
The system uses the engine startup process itself to achieve differential rotation speed control. By leveraging the natural rotation of the engine during startup, the system automatically reduces the differential rotation speed without requiring separate control mechanisms, thus maintaining ease of operation while improving engagement shock suppression.
3Object-affected harmful factors
If the differential rotation speed is reduced before engagement switching, then engagement shock is suppressed, but the switching time is extended
Solution Approach 1:
The engine startup process serves dual purposes: it provides necessary power for vehicle operation and simultaneously reduces the differential rotation speed. This continuous useful action allows the system to achieve engagement shock suppression during a process that would occur anyway, minimizing additional switching time.
Data Source
AI summary
A control device of a vehicle including a first differential portion, a second differential portion, and a second rotating machine, the first differential portion including a first rotating element, a second rotating element to which a first rotating machine is coupled in a power transmittable manner, and a third rotating element coupled to drive wheels, the first differential portion having a differential state controlled through control of the operational state of the first rotating machine, the second differential portion including a fourth rotating element to which an engine is coupled in a power transmittable manner, a fifth rotating element, and a sixth rotating element to which the first rotating element is coupled, the second rotating machine being coupled to the drive wheels in a power transmittable manner, the vehicle further including at least one engagement device out of a first engagement device and a second engagement device as well as a third engagement device, the first engagement device coupling any two rotating elements out of the fourth rotating element, the fifth rotating element, and the sixth rotating element, the second engagement device coupling the fifth rotating element to a non-rotatable member, the third engagement device coupling any one rotating element out of the second rotating element and the third rotating element to the fifth rotating element, the control device comprising: an engagement control portion; and a differential rotation suppression control portion, during running of the vehicle in a rotation stop state of the engine, when the engaged state of only the first engagement device or the engaged state of only the second engagement device out of the first engagement device, the second engagement device, and the third engagement device is switched to the engaged state of only the third engagement device, or when the engaged state of only the third engagement device out of the first engagement device, the second engagement device, and the third engagement device is switched to the engaged state of only the first engagement device or the engaged state of only the second engagement device, the engagement control portion configured to put all engagement devices included in the vehicle out of the first engagement device, the second engagement device, and the third engagement device into the released state and, after a differential rotation speed is made equal to or less than a first predetermined value in an engagement-switching engagement device that is an engagement device to be put into the engaged state after the switching, configured to put the engagement-switching engagement device into the engaged state, and the differential rotation suppression control portion configured to control the operation of the first rotating machine so as to make the differential rotation speed equal to or less than the first predetermined value in the engagement-switching engagement device in the released state of all the engagement devices.