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Research Papers: Flows in Complex Systems

On the Pressure Ripple Measurement in Variable Displacement Vane Pumps

[+] Author and Article Information
E. Mucchi

e-mail: emiliano.mucchi@unife.it

G. Dalpiaz

Engineering Department,
University of Ferrara,
Via Saragat, 1 I-44122 Ferrara, Italy

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received October 2, 2012; final manuscript received March 26, 2013; published online June 10, 2013. Assoc. Editor: Bart van Esch.

J. Fluids Eng 135(9), 091103 (Jun 10, 2013) (11 pages) Paper No: FE-12-1489; doi: 10.1115/1.4024110 History: Received October 02, 2012; Revised March 26, 2013

Vane pumps exhibit pressure ripple in the pressure evolution trend during a complete shaft rotation. Pressure ripple can determine oscillating forces within the system leading to vibration and noise generation. In this context, this paper is focused on the experimental measurement of the pressure evolution in vane pumps by using two different methodologies. Results of measurements are shown, highlighting advantages and disadvantages of both methodologies. In the first method a pressure transducer is directly facing the volume between two vanes, in the second method the sensor is located inside an external chamber where the oil is transferred via a duct suitably designed in the rotor shaft. Briefly, the first method gives better results in terms of pressure evolution but involves some practical problems in the setup: the measurements exhibit pressure offsets strongly dependent on the tightening torque used for sensor mounting and negative pressure values in the low pressure region. The second method is simpler to set up but the results are influenced by the dynamical behavior of the measurement duct carrying oil. In order to avoid resonances of this duct, a vibro-acoustical finite element (FE) model of the oil cavity has been developed. The numerical frequency response functions obtained by the FE model have been used in order to optimize the geometry of the measurement duct, reducing the effects of the resonances of the oil ducts. It is shown that, using this improved methodology, the dynamical components of the measured pressure are not significantly influenced by the frequency response of the measurement duct when the outlet pressures is higher than 50 bar, while for lower outlet pressure the first resonance of the measurement duct is close to the main vane harmonics.

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Figures

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Fig. 1

Exploded view of pump PVH05 with distribution ducts

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Fig. 2

yz and xy sections of pump PVH05

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Fig. 3

(a) Rotor shaft expressly designed for method A. Entran EPB-C1 sensor with lock system is located in the dark gray part of duct; the wires of the sensor are in the light gray part of the duct and are connected to the acquisition system via slip rings. (b) Entran EPB-C1 sensor in the threaded housing.

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Fig. 4

Pump PVH05 during the test with method A

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Fig. 5

Rotor shaft with the two ducts used to measure pressure in spaces and under-vane chambers in method B

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Fig. 6

Bronze cylinder for pressure measurement in method B

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Fig. 7

Pressure evolution in a vane space at outlet pressure of 240 bar for the raw measured pressure signal and for the TSA signal: (a) complete angular rotation and (b) rotational angle range 200–360 deg (high pressure part)

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Fig. 8

Method A: Pressure evolution in a vane space for a complete shaft rotation at outlet pressures of 50, 160, and 240 bar. The reference of the angular coordinate corresponds to the –y direction of Figs. 1 and 2, i.e., when the vane antecedent the vane space in measurement crosses the control piston.

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Fig. 9

Method A: Pressure evolution in a vane space for a complete shaft rotation at outlet pressures of 240 bar with different tightening torque on the pressure transducer. The reference of the angular coordinate corresponds to the –y direction of Figs. 1 and 2, i.e., when the vane antecedent the vane space in measurement crosses the bias piston.

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Fig. 10

Method A: Spectrum amplitude of the high pressure part of the pressure evolution of Fig. 8 for outlet pressure of 240 bar

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Fig. 11

Method B: Pressure evolution in a vane space for a complete shaft rotation at outlet pressures of 50, 160, and 240 bar. The reference of the angular coordinate corresponds to the –y direction of Figs. 1 and 2, i.e., when the vane antecedent the vane space in measurement crosses the bias piston.

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Fig. 12

Method B: Spectrum amplitude of the high pressure part of the pressure evolution of Fig. 11 for outlet pressures of 50, 160, and 240 bar

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Fig. 13

Ducts carrying the oil from the vane space to the sensor location for method B. The light gray part corresponds to the radial and axial ducts which rotates; the dark gray part corresponds to the stator duct where the sensor is mounted. Main dimensions are shown (V is volume, l is length, and d is diameter).

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Fig. 14

Acoustical and structural mesh used in the vibro-acoustical analysis of the measurement duct in method B

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Fig. 15

Restraints used in a section of the X-ring gasket

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Fig. 16

Pressure field at the first natural frequency for measurement ducts of (a) method B and (b) method B1

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Fig. 17

Measurement layout in method B1. (a) The dark gray part are the ducts which take the pressure from a vane space to the measurement chamber; and (b) detail of the ducts carrying the oil from the vane space to the sensor location.

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Fig. 18

Method B1: Pressure evolution in a vane space for a complete shaft rotation at outlet pressures of 50, 160, and 240 bar. The reference of the angular coordinate corresponds to the –y direction of Figs. 1 and 2, i.e., when the vane antecedent the vane space in measurement crosses the bias piston.

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Fig. 19

Method B1: Spectrum amplitude of the high pressure part of the pressure evolution for a complete shaft rotation at outlet pressure of 7, 50, 160, and 240 bar

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Fig. 20

Methods A and B1: Pressure evolutions in a vane space at outlet pressures of 240 bar in rotational angle range 200–360 deg (high pressure part), low-pass filtered 0–2000 Hz

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Fig. 21

Methods A and B1: Spectrum amplitude of Fig. 20

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