Dishwasher Door Latch Return Mechanism for Safer Ajar Opening
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Solution Overview
Problem
Existing dishwasher designs face issues with the automatic opening mechanism, where the latch keeper protrudes far into the room during assisted drying, posing a risk of injury and damage, and rely on expensive and wear-prone electric gear motors, along with unnecessary position switches.
Innovation Solution
A dishwasher with a latch keeper mounted on a push rod, using a return device such as a Bowden cable and direction-changing lever to automatically retract the latch keeper to its initial position, allowing for the use of less expensive actuators and minimizing wear by utilizing tension springs and a simple mechanical linkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the latch keeper remains in the slightly open position after the end of the cycle to assist drying, then the opening gap is large which improves drying efficiency, but the latch keeper protrudes far into the room posing a risk of injury and damage
Solution Approach 1:
The latch keeper is designed to dynamically change its position based on door state. It automatically retracts to a third position when the door is fully opened by the user, minimizing protrusion and eliminating the injury risk while maintaining the large opening gap benefit during assisted drying phase
Solution Approach 2:
The latch keeper operates in periodic cycles: first position for washing, second position for assisted drying, and third position for user-opened door state. This periodic repositioning allows the system to optimize for different operational phases while eliminating the harmful effect when not needed
2Ease of operation
If an electric gear motor is used as the actuator to move the push rod, then the door opening function is achieved, but the motor is expensive and susceptible to wear
Solution Approach 1:
The return device enables the latch keeper to automatically return to its initial position using the door's own opening motion. The Bowden cable mechanism converts the door opening movement into latch keeper retraction, eliminating the need for powered return movement and reducing actuator complexity and wear
Solution Approach 2:
The invention extracts the return function from the actuator by implementing a separate mechanical return device. This allows the actuator to only perform the push rod extension function while the return device handles retraction, simplifying the actuator requirements and reducing wear on moving parts
3Difficulty of detecting and measuring
If two position switches are employed to control the latch keeper positions, then the door position control is achieved, but the device complexity increases
Solution Approach 1:
The latch keeper's movement through different positions automatically triggers the position switch sequence. The mechanical linkage ensures that as the latch keeper moves from first to second to third position, it naturally actuates the appropriate switches without requiring additional sensors or complex control logic
Solution Approach 2:
The position detection function is merged with the mechanical movement of the latch keeper itself. The latch keeper's physical position directly determines which position switch is activated, combining the actuation and detection functions into a unified mechanical system
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 enables safer operation by reducing the risk of injury and damage, while also reducing costs by eliminating the need for expensive electric motors and additional position switches, improving drying efficiency and user convenience.
Implementation Method 1
A return device is configured to return the latch keeper in a direction opposite to the opening direction approximately at least to an initial position upon a further opening of the door
Implementation Method 2
utilizing tension springs and a simple mechanical linkage
Data Source
AI summary
A dishwasher includes a washing tub, a latch keeper disposed on the washing tub and mounted on a push rod, and a pivotable door configured to close the washing tub. The door includes a latching mechanism configured to engage the latch keeper in accordance with a closing of the door. An actuator is configured to move the push rod in an opening direction so as to open the door to an ajar position. A return device is configured to return the latch keeper in a direction opposite to the opening direction approximately at least to an initial position upon a further opening of the door.