Vehicle Shift Control Device Reducing Shock via Clutch Pressure
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Solution Overview
Problem
Existing shift control mechanisms in work vehicles like bulldozers experience shift shock due to speed differences before and after shifting, which can cause discomfort for the operator, as they do not adequately consider the vehicle speed changes during the shifting process.
Innovation Solution
The proposed solution involves controlling the clutch pressure to match the actual vehicle speed with a target speed before connecting a selected speed stage clutch, synchronizing the input and output revolution speeds, and adjusting the clutch pressure to maintain a predetermined vehicle speed change rate during the shifting process, thereby minimizing shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If speed stage clutches are engaged to provide multiple speed stages in the transmission, then the vehicle can operate at different speed ranges, but shift shock occurs during clutch engagement due to speed differences between input and output sides
Solution Approach 1:
The control device performs preliminary actions before clutch engagement by lowering the engagement pressure of the running stage clutch and controlling the vehicle speed to match the target speed. This prepares the system in advance to absorb the speed difference that would otherwise cause shift shock during the actual clutch engagement of the speed stage clutch.
Solution Approach 2:
The running stage clutch acts as an intermediary element to absorb the speed difference during speed stage transitions. By controlling this clutch's engagement pressure and slip characteristics, the system mediates the speed mismatch between input and output sides, preventing direct transmission of shock to the operator.
2Object-affected harmful factors
If the engagement pressure of the running stage clutch is lowered to absorb shift shock, then shift shock is reduced, but the clutch may slip excessively or fail to transmit power effectively
Solution Approach 1:
The control device dynamically adjusts the engagement pressure of the running stage clutch based on the operating conditions and the specific moment in the shifting sequence. The pressure is lowered temporarily during the transition period to absorb shock, then restored to ensure reliable power transmission, making the system adaptable rather than static.
Solution Approach 2:
The control device monitors the actual vehicle speed and compares it with the target speed to determine the appropriate engagement pressure for the running stage clutch. This feedback mechanism ensures that the clutch pressure is optimized to absorb shock while maintaining sufficient power transmission capability throughout the shifting process.
3Object-affected harmful factors
If vehicle speed is controlled to match target speed before clutch engagement, then shift shock is reduced, but the response time for actual speed matching may be insufficient
Solution Approach 1:
The control device initiates speed control actions in advance before the actual clutch engagement occurs. By lowering the running stage clutch pressure and adjusting vehicle speed提前 (in advance), the system ensures that speed matching is already underway or complete by the time the speed stage clutch engages, eliminating delay.
Solution Approach 2:
The control sequence is optimized to perform critical speed matching operations in a condensed time window before clutch engagement. The control device rushes through the speed adjustment process during the brief period when the running stage clutch is disengaging, ensuring speed alignment is achieved without excessive time loss.
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 approach effectively reduces shift shock by ensuring smooth vehicle speed transitions during shifting, enhancing operator comfort and reducing the risk of feeling thrown during gear changes.
Implementation Method 1
matching, by sliding friction members across each other, the difference arising in the selected clutch (transmission element) between the revolution speed on the clutch input side and the clutch output side
Data Source
AI summary
A shift control device and a shift control method for a vehicle for reducing shift shock by taking into account the difference in vehicle speeds before and after shifting. In one of the main inventions, the clutch pressure of another clutch (forward clutch) is controlled to match a target vehicle speed to a calculated actual vehicle speed by the time of start of the connecting operation of a selected speed stage clutch. Since such control is performed so that the vehicle speed is caused to match the target vehicle speed, an actual vehicle speed change rate is held within a predetermined range in at least the instant that the connecting operation of the selected speed stage clutch is started. Also, in another one of the main inventions, as shown in FIG. 7, control is performed to adjust the clutch pressure of the other clutch (forward clutch) so that the vehicle speed change rate reaches a predetermined value in the period from when the connecting operation of the selected speed stage clutch is started until when the connecting operation is completed.