Page 51 - ATZ11 November 2019 Professional

Sensor housing

Sensor module
bonded to
flexible carrier Printed interface for
sensor module
Printed
circuit

Threat bolt

Connector Printed interface
interface Sensor module for periphery
FIGURE 1 Automotive acceleration sensor (left), sensor device (right) (© Bosch)

threat bolt. The sensor module is For the study, sensor-integrated structural ing on the load case. In general, the
positioned and contacted inside plates were manufactured by Resin Trans- integrated SD reduces the achievable
the housing. fer Molding. The SD was integrated into fiber volume compared to a simple struc-
For the integration the packaging of the mid-plane of a symmetrical laminate ture of same thickness. This changes
the acceleration sensor is changed, in the setup, FIGURE 2 (left). A special tool tech- the mechanical performance per se.
following denoted as Sensor Device (SD), nology allows a concealed installation of
FIGURE 1 (right). The SD consists of a the sensor for structural plates with dou-
PRIMARY FUNCTION
0.1-mm-thick flexible circuit carrier, ble-sided even surfaces, FIGURE 2 (right).
ACCELERATION MEASUREMENT
with an interface for the sensor module As a starting point of the study, it
and an interface for the connection was evaluated, whether the transfer The second investigation focus con-
to the periphery. The sensor module of the sensor to an integrated part of a cerned the functional analysis of the
is applied to the carrier by adhesive FRP structure is principally possible. integrated SD. During current operation,
bonding, which avoids a wiring. The In addition, the integration quality of the sensor measures the acceleration
data transfer takes place by printed the sensor-integrated structural plates during a collision.
circuits. For the integration, the SD was examined [4]. With demonstrators of CFRP, func-
has several advantages: A first investigation focus was the tion-specific parameters of the sensing
– The sensor module is positioned mechanics of the sensor-integrated were examined for error patterns [5].
and fixed precisely inside the structures. Specimens made from Car- For this purpose, the demonstrators
structure by the flex carrier. bon Fiber-reinforced Polymers (CFRP) were operated over the standard tem-
– The flex carrier can follow were used. CFRP suits in particular for perature range. The tests were done
complex component shapes. loadbearing vehicle structures. for new parts and after environmen-
– The SD is clearly smaller than The results show that the integrated tal loads.
the current sensor and several SD partly influences the load transfer FIGURE 3 shows exemplarily the influ-
sensor modules can be applied of the structure. The mechanical per- ence of the applied environmental loads
to one flex carrier. formance is raised or reduced depend- on single parameters. In static sensor
operation during the high temperature
storage, the parameters show the typical
behavior within the permissible toler-
ance range, FIGURE 3 (left). In dynamic
sensor operation after applied environ-
mental loads the sensor sensitivity is
picked out, FIGURE 3 (right). Differences
to the new part appear after temperature
changes and humidity. An excess of
the tolerance limits is still not given.
All together, the demonstrators
reveal no function-specific error pat-
terns. Nevertheless, for the evidence
of the unlimited functionality for the
passive vehicle safety this must be
FIGURE 2 Laminate setup (left), sensor-integrated FRP structure (right) (© Bosch) validated comprehensively.
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