Journal of Chongqing University (English Edition) [ISSN 1671-8224]
Vol. 9 No. 4
December 2010
208
Article ID: 1671-8224(2010)04-0208-08
To cite this article: WEN De-sheng, WANG Zhi-li, LV Shi-jun, GUO Gao-feng, DU Xiao-jie, Tetsuhiro TSUKIJI. Single-acting double-stator multi-pumps and multi-motors [J]. J
Chongqing Univ: Eng Ed [ISSN 1671-8224], 2010, 9(4): 208-215.
Single-acting double-stator multi-pumps and multi-motors
WEN De-sheng
1,2,†
, WANG Zhi-li
1,‡
, LV Shi-jun
1
, GUO Gao-feng
1
, DU Xiao-jie
1
, Tetsuhiro TSUKIJI
2
1
College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, Hebei Province, P. R. China
2
Faculty of Science and Technology Department of Engineering and Applied Sciences, Sophia University, Tokyo 102-8554, Japan
Received 27 October 2010; received in revised form 10 November 2010
Abstract: We investigated a series of novel motors and pumps with a new structure called double-stator. Double-stator can be
used as pump or motor just for the working condition on demand. A certain amount of pumps or motors are formed in one shell
and these subpumps or submotors can work alone or in company without influence on other pumps or moters. This kind of
double-stator pumps (motors) are called multi-pumps (multi-motors). Through the analysis of multifarious connection modes of
single-acting double-stator multi-pumps and multi-motors, the mathematical expressions of output flow rate, rotational speed and
torque are acquired. The results indicate that different flow rates can be provided by one fixed displacement double-stator multi-
pump system under the condition of an unalterable driven speed. Likewise, under the terms of a fixed input flow and without
complex variable mechanisms, the functions of double speeds, multiple speeds and even differential connection can be realized by
a double-stator multi-motor system with various output rotational speeds and torques.
Keywords: multi-pump; multi-motor; multiple flow rate; multi-torque; multi-speed
CLC number: TH137.5 Document code: A
1 Introduction
a
The biggest defect of hydraulic transmission is its
low efficiency; hence, the study on energy saving has
always been a key problem [1-2]. In a hydraulic
transmission system, the speed control circuit plays an
important role and has great influence on selecting
other hydraulic circuits [3].There are a variety of ways
to control the speed in a hydraulic system. In general,
they can be divided into two categories: throttle speed-
regulating circuits and volume speed-regulating circuits.
Most applications of hydraulic circuits originally come
from the above basic speed control circuits [4].
However, some disadvantages exist in the two basic
categories of circuits. For a throttle speed-regulating
†
WEN De-sheng (闻德生): wendesheng@ysu.edu.cn.
‡
Corresponding author, WANG Zhi-li (王志力): chily666@163.com.
Funded by the National Natural Science Foundation of China (No.
50975246).
circuit, when the flow rate of oil supplied by a pump is
higher than that the actuator needs, the relief valve is in
the state of overflow which incurs a great energy loss.
When hydraulic oil passes a control valve, there will be
throttle loss because of the choking effect; thus the
circuit has a very low efficiency. Due to the great
power loss, temperature will increase accompanied by
loud noises. Therefore, a throttle speed-regulating
circuit is only suitable for low-power hydraulic
transmission and the range of the speed of the
transmission system is not wide [5-6]. For volume
speed-regulating circuits, most of them are used as
closed circuits. The disadvantage of this kind of
circuits is poor heat dissipation. To compensate for
leakage, recharging oil devices are required [4] which
makes the circuit more complicated. A volume-throttle
speed-regulating circuit commonly used in a non-
variable speed motor drive variable displacement pump
not only has high demands in oil cleanliness due to the
complicated variable mechanism, but also is subject to
an unchangeable rotating pump speed. Thus, the