System and method for variable compression ratio engine

A technology of compression ratio and engine, applied in engine control, machine/engine, gear transmission mechanism, etc., can solve problems such as transient acceleration and slow acceleration affecting the engine

Pending Publication Date: 2020-01-03
FORD GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

On the other hand, when the brake function is activated and the control shaft is locked, the engine may not be able to transition quickly from high to low compression
Since the rate at which the engine can switch compression ratios during transient conditions depends on the speed at which the VCR control shaft can be moved by the VCR actuator, the braking function can negatively affect the engine's transient acceleration issues
Slow transitions can lead to sluggish acceleration that is off-putting to the driver

Method used

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  • System and method for variable compression ratio engine
  • System and method for variable compression ratio engine
  • System and method for variable compression ratio engine

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Embodiment Construction

[0020] The following description relates to systems and methods for an engine system configured with a variable compression ratio (VCR) mechanism, as referenced Figure 1-2 The engine system is described. The controller can be configured to execute control programs such as Figure 3-4 An example procedure to lock the band brakes coupled to the VCR control shaft to maintain a fixed CR setting, and to vary the brake pressure applied by the band brakes to improve CR transitions. Such as Figure 5 Elaborating, the brake pressure can be adjusted during CR transitions based on the engine torque applied to the control shaft, which is known from engine speed-load ( Figure 8 ). Brake pressure applied via band brakes can be adjusted via hydraulic or electric actuators, such as Figures 6A-6B Elaborate. The controller may lock the band brakes when the engine's CR setting is in the high or low zone, and unlock the band brakes and adjust brake pressure when the CR setting is in the n...

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Abstract

Methods and systems are provided for maintaining a compression ratio of an engine via a brake and while disabling an electric current applied to an actuator of the associated variable compression ratio mechanism. A braking force applied via the brake on a compression ratio control shaft is varied before and during a compression ratio transition to move the control shaft at a desired velocity. Brake torque application is coordinated with motor torque from a VCR actuator and engine torque applied on the control shaft to enable a smooth CR transition.

Description

technical field [0001] The description generally relates to methods and systems for variable compression ratio engines. Background technique [0002] The compression ratio (CR) of an internal combustion engine is defined by the cylinder geometry, which is the ratio of cylinder volumes when the piston is at bottom dead center (BDC) relative to top dead center (TDC). Higher compression ratios generally correlate with higher thermal efficiency and engine fuel economy. A variable compression ratio (VCR) engine can mechanically vary the compression ratio for each cylinder between high compression ratio (HCR) and low compression ratio (LCR) settings. For example, by mechanically shifting the position of the piston in the cylinder bore so that it is closer or farther from the top of the cylinder bore (such as via an eccentric coupled to the piston), the volume at TDC and thus the compression ratio setting can be changed. The HCR setting can be selected at light to moderate loads ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F02D15/04F02B75/04
CPCF02B75/045F02D15/04F02D15/02F02D2250/18F16D49/08F16D49/12F16D2121/06B60W10/06B60W10/10B60W10/18B60W30/182B60W2510/06B60W2710/06B60W2710/1005B60W2710/18F02D2200/1002F02D2200/101F02D2200/50F02D2700/03
Inventor 法比安·加多克里斯多夫·格鲁格拉
Owner FORD GLOBAL TECH LLC
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