Brake Float Level Sensor - Digi-Key

Brake Float
Float Level Sensor
REED RELAYS REED SENSORS REED SWITCHES
Introduction
When applying one’s foot to the brake pedal, it is taken for granted that the
braking mechanism will begin to slow or stop the vehicle. A hermetically sealed
reed switch plays a key reliability role by monitoring that the brake fluid level is
maintained at its proper level. Low brake fluid level could mean the loss of the
vehicle braking system.
Figure 1. Complete Brake Float Level Sensor
Features
• All inclusive brake fluid sensor complete with
switching element (Reed Switch), Float, and
magnet
• Hermetically sealed
• Dynamically tested contacts
Figure 2. Brake Fluid above low level- Reed Switch not activated
• Reliable switching
• Accurate control of the open and closure points
• Wide hysteresis preventing on/off cycling
• Ability to operate at very hot and cold
temperatures in an under the hood environment
• Low cost
• Housing vapor sealed
• Different headers available for different
vehicles
• Millions of reliable switching operations
• Accurate control of the open and closure points
Applications
• Sensing the fluid level in brake fluid reservoirs
• Sensing fluid level in gasoline, oil and other
liquid reservoirs
Figure 3. Brake Fluid Low Position- Reed Switch closed activating lamp indicator light
• Coolant overflow fluid system sensing
MEDER’s Reliable Reed Approach To Brake Fluid Level
Sensing Systems
Designing a sensing system for under the hood of a vehicle presents difficult
requirements. The sensor must operate at extreme temperatures that are as
low as -40°C and as high as 125°C. This dirty environment is typically visited
by oil, gasoline, brake fluid, salt water and a host of solid particulates.
MEDER’S approach has been to use only the most reliable technology to insure
quality operation and long reliability in the field for the life of the vehicle.
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: info@meder.com
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: salesusa@meder.com
Page 1 of 2
www.meder.com
Brake Float
Float Level Sensor
REED RELAYS REED SENSORS REED SWITCHES
Specifications (@ 20°
20°C)
LSS Series
Operate specs
Min Max Units
Must close distance
distance
Ref Ref
mm
Must open distance
Ref Ref
mm
Hysteresis
Load Characteristics
Switching voltage
Switching current
Carry current
Contact
Contact rating
Static Contact
resistance
Dynamic contact
resistance
Breakdown voltage
Operate time
Release time
Operate Temp
Storage Temp
Min Max Units
200
0.5
1.0
10
150
200
200
0.4
0.05
-40 125
-65 150
V
Amps
Amps
Watts
mΩ
mΩ
V
msec
msec
°C
°C
Since this sensor requires some electrical circuitry, using a printed circuit board
with plated thru solder holes guarantees reliable connections using an
automated wave soldering system. Others have chosen welding technology
which can guarantee a good connection, but can also damage the delicate
hermetic seal of the reed switch with its high temperature point contact and its
tough mechanical approach. This poses an even bigger problem in the field if a
slight crack of the reed switch seal occurs during assembly, as it could take up
to a year or more for enough gas and/or moisture to leak into the capsule to
oxidize the contacts. Then if the brake fluid drops below acceptable limits the
contacts would fail to close; therefore, not alerting the driver that a critical
situation has developed. Figures 2 and 3 show the proper operating sequence.
Also, part of our design criteria is to build sufficient hysteresis into the operation
of the sensor. This insures once the sensor activates, it will not go on and off
with every sway of the vehicle or bump in the road.
Another critical element is the acknowledgement that during assembly problems
can occur. MEDER tests all sensors 100% for all operating conditions, but in
addition tests for dynamic contact resistance (DCR). Essentially this test is a
guard against the many faults that can occur during assembly. If the reed
contacts have any internal contaminations; or the reed capsule has been
stressed or a slight crack has occurred, this DCR will detect these conditions
and reject the sensor. This testing is all carried out in an automated testing
system that is independent of any operator, and rejected parts
are
automatically placed in a lock box. MEDER’s design for manufacturing
approach provides a long reliable life in the field.
The header and sleeve shown in the dimensional diagram have several other
potential options allowing different connectors to be used, as well as the ability
to fit into several other types of brake fluid reservoirs.
Consider some of the below liquid level sensors for similar brake float sensor
applications.
Liquid Level Series
Series
KSSKSS-BV10113
BV10113
LS01
LS02
LS03
Dimensions
mm
Illustration
inches
W
17
0.669
H
44
1.732
L
W
H
L
W
H
L
58
19
24
42
19
24
75
2.283
0.748
0.945
1.654
0.748
0.945
2.953
W
25
0.984
H
25
0.984
L
80
3.150
**Consult
the factory for more options not listed above.
**
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: info@meder.com
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: salesusa@meder.com
Page 2 of 2
www.meder.com