Top Loading Washing Machines Use Reed Sensors to - Digi-Key

Top Loading Washing Machines Use Reed
Reed Sensors to
Detect
Detect if the Lid is Open or Closed
REED RELAYS REED SENSORS REED SWITCHES
Introduction
Some top loading clothes washers have the drum rotating perpendicular to the
door and some have the drum rotating in the same plane as the top. In the
former of the two rotating directions, opening the top can be very dangerous if
the drum continues to rotate. In the case of the latter rotating drum is less
dangerous, but trouble may still occur. To avoid laws suits, appliance designers
once again have turned to MEDER engineers to help solve the problem.
Figure 1. MK14 Sensor physical layout
Features
• Magnet and Reed Sensor are isolated and
have no physical contact by typically having
the magnet mounted the top lid of the washing
machine, and the Reed Sensor is mounted on
the chassis of the washing machine
strategically placed such that the magnetic field
of magnet will be sensed when the top is
opened and closed.
• The reed switch used in the Reed Sensor is
hermetically sealed and is therefore not
sensitive to rough, wet, moist, high
temperature environments
Figure 2. Washing machine lid is closed and magnetic field closes the reed switch
activating the washing machine.
• The magnet is not affected by its environment
• Tens of millions of reliable operations
• Cylindrical hole and screw fastening mounting
• Contacts dynamically tested
Applications
• Ideal for sensing the top lid opening and
closing with top loading washing machines
• Ideal for applications sensing any kind of door
or lid opening or closing in a host of different
configurations
Figure 3. Washing machine lid is open moving the magnetic field of the magnet away from
the reed switch causing the contacts to open and the washing machine to turn OFF.
MEDER’s reed sensors sense the position of the top lid of a
washing machine
Some top loading clothes washing machines have their drums rotating
perpendicular to the top of the washing machine and rotate in the plane of the
top of the appliance. Opening the top of the appliance while the drums are
rotating can be dangerous particularly when the drum is rotating in the
perpendicular direction. Appliance designers working MEDER’s engineers have
solved the problem by using a reed sensor to sense open and closing of the lid.
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: [email protected]
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: [email protected]
Page 1 of 2
www.meder.com
Top Loading Washing Machines Use Reed
Reed Sensors to
Detect
Detect if the Lid is Open or Closed
REED RELAYS REED SENSORS REED SWITCHES
Specifications
Operate specs
Min Max Units
Must close distance
5
25
mm
Must open distance
5
25
mm
Hysteresis
Load Characteristics
Characteristics
Switching voltage
Switching current
Carry current
Contact rating
Static Contact
resistance
Dynamic contact
resistance
Breakdown voltage
Operate time
Release time
Operate Temp (MK06)
Storage Temp (MK06)
Typical 50%
Min Max Units
200
0.5
1.5
10
150
200
320
0.5
0.1
-20 85
-35 85
Volts
Amps
Amps
Watts
mΩ
mΩ
Volts
msec
msec
°C
°C
A magnet is mounted to the top lid. The reed sensor is mounted on the chassis
of the washing machine strategically placed such that it will sense each time the
top lid is opened or closed. In this position the sensor is directly wired to the
washer electronics. Now if the washing machine is in the middle of a cycle with
the top closed, the reed sensor is in the closed position. If someone attempts to
open the top, the reed sensor opens. This change of state is sensed by the
electronics and will immediately turn off the drum eliminating the existing
danger of the rotating drum. When the top is re-closed the sensor switch closes
giving the ‘green light’ to the electronics to resume operation.
Because MEDER’s sensors use hermetically sealed reed switches that are
further packaged in strong high strength plastic, they can be subject to rough
treatment and environmental concerns such as water sprays, and moisture
without any loss of reliability.
The reed sensor is an excellent choice because it can operate reliably over a
wide temperature range, and represents an economical way to carry out the
sensing function. MEDER’s cylinder packages as well as screw fastening
packages having lead wires for remote attachment to the electronics are ideally
suited for this application.
Cylindrical Panel Mount Series
Series
MK03
MK03
Dimensions
mm
Dia
5.80
L
25.5
Illustration
inches
0.244
1.004
MK14
MK14
Dia
L
4
25.5
0.157
1.004
MK18
MK18
Dia
L
5
17
0.197
0.669
MK20/1
MK20/1
Dia
L
2.72
10
0.107
0.394
Rectangular Screw Flange Mount Series
Series
MK04
MK05
MK05
MK12
MK12
Dimensions
mm
W
13.9
H
5.9
L
23.0
W
19.6
H
6.1
L
23.2
W
H
L
14.9
6.9
32.0
Illustration
inches
0.547
0.232
0.906
0.772
0.240
0.913
0.587
0.272
1.260
**Consult
our factory for your specific design requirements.
**
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: [email protected]
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: [email protected]
Page 2 of 2
www.meder.com