Floor cleaning machine with fill level measurement for dirty fluid tank
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Solution Overview
Problem
Existing floor cleaning machines struggle to reliably determine when the dirty water tank is full, especially on smooth floors with large amounts of water, leading to incorrect motor speed and current readings that can result in premature suction shutdown.
Innovation Solution
A measuring device that detects the differential pressure between the dirty water tank and the suction line, generating signals to indicate whether the liquid level has reached the maximum permissible level, allowing for accurate determination of the tank's fill status without electrical contacts that can be affected by dirt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor speed or current is used to determine float valve closure, then the system can detect tank fill level, but it cannot reliably distinguish between normal operation on smooth floors and actual tank overflow
Solution Approach 1:
A differential pressure switch is introduced as an intermediary device to detect the fill level status. The switch measures pressure differential between the tank interior and exterior, providing a reliable indication of float valve closure that is independent of motor performance variations during normal operation on different floor types
Solution Approach 2:
The patent replaces the indirect electrical measurement method (monitoring motor speed/current) with a direct mechanical pressure sensing system. The differential pressure switch provides direct physical measurement of the pressure difference caused by float valve closure, eliminating the ambiguity present in electrical parameter-based detection
2Reliability
If a float valve is used to close the suction connection at maximum level, then the tank can be protected from overflow, but the system lacks reliable feedback to distinguish actual overflow from normal high water usage
Solution Approach 1:
The differential pressure switch provides immediate feedback when the float valve closes by detecting the pressure differential between tank interior and exterior. This feedback mechanism reliably indicates fill status without being influenced by variations in water usage patterns during normal operation
Solution Approach 2:
The pressure differential measurement acts as an intermediary indicator that translates the mechanical action of float valve closure into a detectable signal, providing clear information about tank fill status independent of operational conditions
3Measurement precision
If electrical contacts are used inside the dirty water tank for level detection, then the system can monitor fill level, but the contacts are severely affected by dirt and cleaning agents
Solution Approach 1:
The sensing mechanism is extracted from the contaminated environment inside the tank. The differential pressure switch measures pressure differential across the tank wall, eliminating the need for electrical contacts to be physically present in the dirty water environment where they would be affected by dirt and cleaning agents
Solution Approach 2:
The tank wall itself serves as an intermediary that transmits pressure information from the interior to the exterior sensing mechanism. This allows level detection without direct contact between sensing elements and the contaminated liquid environment
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 reliable operation of the floor cleaning machine on smooth floors with large water usage by accurately distinguishing between normal cleaning and tank overflow conditions, preventing unnecessary suction shutdowns and ensuring safe and efficient operation.
Implementation Method 1
a measuring device (33) configured to detect a differential pressure between a first gas pressure in the wastewater tank (9) and a second gas pressure in the suction line (17)
Implementation Method 2
a float valve (21) which closes the connection (19) when the liquid level in the dirty water tank (9) reaches a maximum level
Implementation Method 3
a suction unit (15) driven by a motor and connected to the dirty water tank (9) via a suction line (17) on the suction side via a connection (19) provided on the dirty water tank (9) to generate a vacuum
Data Source
Figure 1
Figure 2
AI summary
A floor cleaning machine is shown and described, comprising a dirty water tank (9) and a suction device (7) attached to a machine frame (1) for extracting liquid from the floor surface (5). The suction device (7) is connected to the dirty water tank (9). The floor cleaning machine also has a suction port (15) which is connected to the dirty water tank (9) via a suction line (17) to create a vacuum within the dirty water tank (9). A float valve (21) is provided in the dirty water tank (9) and is designed to close the connection (19) to the suction line (17) when the liquid level in the dirty water tank (9) reaches a maximum level.Furthermore, a measuring device is provided which is configured to detect a differential pressure between a first gas pressure in the wastewater tank (9) and a second gas pressure in the suction line (17) and to generate a first signal when a differential pressure threshold is undershot and/or to generate a second signal when the differential pressure threshold is exceeded. The present invention also relates to a method for operating a floor cleaning machine.