Mechanically Controllable Valve Drive With Reduction Gearing
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Solution Overview
Problem
Existing valve train arrangements for internal combustion engines face challenges in precise adjustment of valve lift, limited variability, especially during partial cylinder deactivation, leading to increased fuel consumption and emission values.
Innovation Solution
The implementation of a mechanically controllable valve train with actuators connected via a reduction gearing system, comprising a straight-toothed spur gear and worm gear, decoupling the actuator from axial forces and allowing for precise control of gas exchange valves, particularly with a reduction ratio between 5/1 and 10/1, and incorporating a worm wheel shaft and eccentric control cam for enhanced flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If valve lift is adjusted via cam of eccentric element, then valve lift position can be set, but adjustment precision is insufficient and variability is limited
Solution Approach 1:
The valve lift adjustment mechanism is segmented into multiple independent components: the camshaft provides base rotation, the eccentric element provides radial displacement, and the reduction gearing (worm gear + straight-toothed spur gear) provides precise angular multiplication. This segmentation allows each component to contribute to the overall precision and variability of valve lift adjustment.
Solution Approach 2:
The reduction gearing acts as an intermediary between the actuator and the adjusting element. The worm gear engages with the straight-toothed spur gear to provide a mechanical advantage, multiplying the actuator's rotational movement into precise, controlled adjustments of the eccentric element's orientation, thereby achieving high adjustment precision.
2Speed
If rapid adjustment from maximum lift to minimum lift is required at high engine speed, then response time is reduced, but existing mechanisms cannot achieve this speed
Solution Approach 1:
The patent replaces direct mechanical coupling with a reduction gearing system that uses a worm gear and straight-toothed spur gear. This mechanical substitution allows the actuator to operate at lower speeds while achieving high-speed response at the valve lift adjustment point through the gear ratio multiplication, effectively decoupling actuator speed from response speed.
3Device complexity
If actuator is directly coupled to adjusting element, then control is simple, but mass inertia increases and precision decreases
Solution Approach 1:
The reduction gearing system with worm gear and straight-toothed spur gear serves as an intermediary that decouples the actuator from the adjusting element. This allows the use of a smaller, lighter actuator with lower mass inertia while still achieving precise control through the mechanical advantage provided by the gear system.
Solution Approach 2:
The reduction gearing changes the rotational speed and torque parameters between the actuator and the adjusting element. By providing a gear ratio between 5/1 and 10/1, the system transforms the actuator's low-speed, low-torque output into high-speed, high-torque movement at the eccentric element, effectively reducing the required actuator mass inertia.
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
This solution enhances the variability of valve lift settings, reduces fuel consumption, and decreases emission values by enabling rapid adjustments and minimizing mass inertia, thus improving engine efficiency.
Implementation Method 1
the gearing being composed of a straight-toothed spur gear and a worm gear, a worm gear shaft being provided and the adjusting element is at least partially designed as a worm wheel
Implementation Method 2
the reduction gearing, the gearing being composed of a straight-toothed spur gear and a worm gear
Implementation Method 3
the adjusting element has at least one eccentric element which acts on the transmission arrangement
Implementation Method 4
the adjustment element can advantageously have an eccentric element designed as a control cam
Implementation Method 5
acts on the transmission arrangement against a biasing force of a spring element
Data Source
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AI summary
The invention relates to a mechanically controllable valve train with at least one gas exchange valve, onto which a transmission arrangement (32) acts by means of an end face, wherein the transmission arrangement (32) is movably mounted in the cylinder head by means of bearing means and wherein the transmission arrangement (32) is operatively connected with a valve lift adjustment device (66) and a camshaft (48), wherein the valve lift adjustment device (66) has a rotatable adjusting element (50) with at least one eccentric element, which acts on the transmission arrangement (32) against a preload force of a spring element, such that different valve lift positions can be set, wherein the valve lift adjustment device (66) has an actuator (78) which is operatively connected to the adjusting element via a reduction gear transmission (106).