Variable Valve Lift Apparatus with Hydraulic Cam Switching
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Solution Overview
Problem
Conventional valve lift apparatuses in automotive engines have a fixed valve lift amount, making them inadequate for adjusting gas introduction or exhaust at varying driving speeds, as they are either insufficient for low speeds or excessive for high speeds.
Innovation Solution
A variable valve lift apparatus with a low lift body and high lift body connected by a hydraulic system, including a hydraulic pressure adjusting valve and actuator, allowing for adjustable valve lift through different cam operations and restoring forces, enabling adjustment of valve open and close amounts and modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the valve lift apparatus is designed for low driving speeds, then the valve open time and amount are sufficient for low speeds, but they are not sufficient for high speeds
Solution Approach 1:
The valve lift apparatus employs a variable lift body that can dynamically switch between low lift and high lift configurations. The low lift body and high lift body are selectively connected or disconnected through hydraulic pressure control, allowing the system to adapt its valve lift characteristics in real-time based on driving conditions. This dynamic reconfiguration enables the same apparatus to provide appropriate valve open time and amount for both low and high speeds.
Solution Approach 2:
The system changes the physical parameter of valve lift amount by switching between different cam configurations. The low lift cam and high lift cam provide different lift characteristics, and the hydraulic pressure adjusting valve controls which cam configuration is active. By changing the operational parameters (lift amount, open time) through hydraulic control, the apparatus can optimize performance across different speed ranges.
2Speed
If the valve lift apparatus is designed for high speeds, then the valve open time and amount are sufficient for high speeds, but they are excessive for low speeds
Solution Approach 1:
The variable lift body allows the system to dynamically reduce valve lift characteristics when operating at low speeds. By disconnecting the high lift body and connecting the low lift body through hydraulic pressure control, the apparatus prevents excessive valve open time and amount at low speeds, while maintaining the capability for high-speed operation when needed.
Solution Approach 2:
The system selectively changes the valve lift parameters by switching between low lift and high lift cam configurations. The hydraulic pressure adjusting valve controls the connection state of the low lift pin to the low lift pin connecting portion, thereby changing the operational parameters to match the required driving conditions and avoiding excessive valve operation at low speeds.
3Ease of manufacture
If a fixed cam shape is used, then the valve lift apparatus has a fixed valve lift amount, but it is impossible to adjust the amount of gas being introduced or exhausted
Solution Approach 1:
The valve lift apparatus is segmented into distinct functional components: a low lift body with low lift cam, a high lift body with high lift cam, and a variable lift body that connects them. This segmentation allows each component to have a simple, fixed design (easing manufacturing) while the overall system achieves adjustability through the selective connection of these segmented parts via hydraulic control.
Solution Approach 2:
The variable lift body serves multiple functions by being capable of connecting to either the low lift body or the high lift body. This multi-functionality allows a single apparatus to provide different valve lift characteristics (low lift mode, high lift mode, and intermediate modes) without requiring multiple separate devices, thereby achieving both manufacturing simplicity and operational adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables flexible valve lift adjustment, achieving optimal gas flow at various speeds by allowing for different operational modes, such as CDA, low lift, and high lift modes, improving engine performance across speed ranges.
Implementation Method 1
a hydraulic pressure adjusting valve disposed on the end lever for selectively supplying hydraulic pressure to the hydraulic line
Implementation Method 2
a low lift pin elastic member disposed in the low lift pin inserting portion and supplying a restoring force to the low lift pin
Implementation Method 3
a high lift elastic member disposed in the high lift pin inserting portion for supplying a restoring force to the high lift pin
Data Source
AI summary
A variable valve lift apparatus includes an end lever; a variable lift body connected to the end lever, and rotatable around the end lever, a valve mounted on the variable lift body; and a low lift cam operable to open and close the valve. The variable lift body includes a high lift body, and a low lift body rotatable around the high lift body. A low lift connecting portion selectively connects the low lift body and the high lift body.