Optimization of orifice position in particle-excitation valve for proportional flow control
Hirooka et al. Robomech J
Optimization of orifice position in particle-excitation valve for proportional flow control
Daisuke Hirooka 0
Tomomi Yamaguchi 0
Naomichi Furushiro 0
Koichi Suzumori 2
Takefumi Kanda 1
0 Department of Mechanical Engineering, Kansai University , 3-3-35, Yamate-cho, Suita-shi, Osaka 564-8680 , Japan
1 Graduate School of National Science and Technology, Okayama University , 3-1-1 Tsushima-naka, Okayama 700-8530 , Japan
2 Graduate School of Engineering, Tokyo Institute of Technology , 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 , Japan
This paper reports an improvement of the particle-excitation flow control valve. The valve that we have designed in previous reports can control air flow, using particle excitation by piezoelectric resonance, and has the following advantages: small size, lightweight, high response and continuous airflow control. However, in our previous models, the relationship between the driving voltage and the flow quantity was nonlinear. In this report, we improved the valve to realize proportional flow control. The valve consists of the orifice plate, that has some orifices, and steel particles to seal the orifices and piezoelectric transducer. It controls air flow by the voltage applied to the transducer. For proportional flow control, it is important to adjust the orifice position adequately. In this report, we optimized the orifice position, considering resonance condition of the valve. We designed the experimental prototype using a boltclamped Langevin type transducer and decided orifice position. And we evaluated its vibration properties and flowrate characteristics. The experimental results showed that our designed prototype can proportionally control airflow.
Proportional flow control valve; Pneumatic valve; Pneumatic actuator; PZT; Flow control valve
Background
A pneumatic actuation system has many advantages,
including lightweight, safety, and low cost. Because
pneumatic actuators have compliance, they are widely
researched for human support devices [
1–5
]. Recently,
the actuators are examined as the application of
artificial muscles and soft actuators [
6–10
]. However, it is
difficult to control pneumatic equipment since air is
compressible and has nonlinear characteristics.
Therefore, highly controllable devices are in great demand.
Many kinds of pneumatic control devices have been
researched [
11–28
]. Especially, piezoelectric (PZT)
actuators are widely used [
14–22, 24–28
] because some
of these actuators have high response and large power.
Because the strokes of PZT actuators are very small and
must be increased, some researches use laminated PZTs
[
17–19
], bimorph structure [
16
], motors [
20, 21, 24
], or
displacement amplifier mechanisms [
25–28
]. Especially
for proportional or servo valves, since the stroke of the
actuated part is critical, displacement amplifier
mechanisms are used. A valve with displacement amplifier
mechanisms is heavy and large. We designed flow
control valves using particle excitation mechanism whose
advantages are small size and high response [
29–32
]. This
control mechanism uses PZT resonance frequency and
does not need the displacement amplifier mechanism.
In previous report, we demonstrated its basic structure
and confirmed that it has potential to provide a large flow
rate [
29
]. We showed new mechanism of the valve using
deferent types of particles for stable flow control [
30
]. We
discussed orifice condition of the valve and designed
prototype that can control air flow continuously [
31
]. And
we expanded orifices diameter to increase flow quantity
and checked responsiveness of the valve [
32
]. However,
the flow conditions of the prototypes were nonlinear. In
this report, we proposed a new model of
particle-excitation valve that can realize the proportional flow control.
For proportional flow control, we optimized the orifice
position considering vibration mode. Firstly, we showed
the basic mechanism and then specifically explained its
design, how the valve makes the flow condition
proportional. Secondly, we designed a prototype optimizing
the orifice position. To decide orifice position, we used
the approximation of orifice deformation shape. Next
we showed the designed prototype’s basic
characteristics. Finally, we provided the results of a flow rate change
experiment and explained the flow rate characteristics.
Proportional mechanism using particle excitation valve
Basic control mechanism of particle excitation
Firstly, we explain the basic principle of the previously
designed particle-excitation mechanism [
29
]. Figure 1
shows a cross section of a flow control valve and
establishes its basic working principle using particle
excitation. This valve consists of an orifice plate, a piezoelectric
transducer, and steel particles. The orifice plate is located
at the transducer’s antinode. Figure 1a depicts the valve
in non-driving state. Airflow is supplied from the airport,
(...truncated)