128 Figure 6.30: Frequency response test mounted on the test bench
The figure depicts the frequency response test setup with the pump, direction control valve and associated connections that were made to perform the test.
129 Table. 6.4 Features of sensors and main elements of the apparatus used in the present
research
Parameter to be measured Sensor Used
Inlet pressure to valve Pressure transducer (0 – 400 bar range) Bridge pressure Pressure transducer (0 – 400 bar range) Load Sensing Pressure Pressure transducer (0 – 400 bar range)
Work port A Pressure transducer (0 – 400 bar range)
Work port B Pressure transducer (0 – 400 bar range)
Pilot Pressure Pressure transducer (0 – 400 bar range)
Main Spool Displacment Linear Variable Differential Transformer (-15 to +15)
Pressure Compensator Dispalcement Linear Variable Differential Transformer (-15 to +15)
Inlet flow measurement to valve Flow meter Outlet flow measurement port A Flow meter Outlet flow measurement port B Flow meter
The figure describes the details of the manifold, pressure tapping points and LVDT attachment
Table 6.5: Description of the parts in the figure Part No. Description
1 Rear Manifold plate
2 Solenoid
3 Linear Variable Differential Transformer 4 LVDT attachment for connection to main spool
5 Front Manifold plate
6 Bridge pressure tapping point
7 LVDT connected to pressure compensator
130 Figure 6.31 Manifold for DPX 100 with instruments and pressure tapping points
The figure 6.32 shows a detailed view of the attachment of the LVDT to the main spool.
As it can be seen in the illustration part 4 is an attachment to connect the LVDT body with the housing of the pilot chamber. Part 8 is another attachment made to connect the LVDT spool with the main spool of the DPX 100. In this manner the LVDT has been rigidly connected to the main spool.
Figure 6.32 CAD model of the LVDT and main spool connection
1
2
3
4
5
6 7
4 8
131 The connection of the pressure compensator was done in a similar manner as can be seen in figure. The complexity in rigidly connecting the LVDT to the pressure compensator is that the PC has a fine orifice which has to be recreated in any attachment that is developed.
This has been realised by using part A which has a small orifice of 0.5mm drilled and then a 1mm hole drilled at right angles to allow the sensed pressure to pass through. The complete attachment comprises of LVDT part 7 connected to the valve housing through part 9. Part 10 is the special LVDT and Pressure Compensator spool attachment.
Figure 6.33 Instrumentation of the pressure compensator
The figure depicts the view of the valve block DPX 100 with the LVDT’s and LVDT attachments to connect to the main spool and to the pressure compensator.
Figure 6.34: Exploded view of the complete position measurement setup on the valve
Two types of the tests were carried out using the instruments that were mounted on the valve block and are described in this section:
9 7 10
A
PC
132 1. The functioning of the DPX 100 as a single slice.
2. The functioning of two DPX 100 slices
6.5.1 Functioning of the DPX 100 as a Single Slice
Table.6.6. Features of sensors and main elements of the apparatus used in the present research
Sensor Type Main features
M Prime mover ABB®, 4-quadrant electric
motor, 75 Kw
P Pump CASAPPA® MVP60, 84 cm3/r
P1 Strain gage WIKA®, Scale: 0..40 bar,
0.25% FS accuracy P2 – P3 – P4 – P5 –
P6 – P7– P8 Strain gage WIKA®, Scale 0..400 bar, 0.25% FS accuracy
Q2 Flow meter
VSE® VS1, Scale 0.05..80 l/min, 0.3% measured value
accuracy
T Torque/speed meter
HBM® T, Scale: 0..500 Nm, 12000 r/min Limit Velocity,
0.05 Accuracy Class
Θ Incremental encoder
HEIDENHAIN® ERN120, 3600 imp./r, 4000 r/min Limit velocity, 1/20 period accuracy LVDT Linear variable differential
transformer Magnet Schuz AVAX 015
The figure represents the schematic of the test setup that was developed to test the functioning of the DPX 100 functioning as a single slice. To carry out the test it was decided that it would be best to study the valve with a fixed displacement pump, in this way the effects of LS compensation and feedback could be eliminated. To achieve this the pump’s load sensing line was connected to the pump outlet and in this way the flow compensator was kept in a fixed position and the pump always maintained maximum displacement. A flow meter was set at the inlet of the valve and a pressure transducer to determine the inlet system pressure. The main spool was actuated by setting a pilot pressure of 35 bar with the gear pump following which the current to the proportional flow control solenoids were altered to displace the main spool.
The following tests were carried out on a single slice and the following parameters studied:
133 1. Spool Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A and then the current brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool.
The displacement of the pressure compensator was studied as the main spool was shifted to maximum displacement and then closed.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
2. Pressure Compensator and Piston Check Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A and then the current brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool.
The displacement of the pressure compensator was studied as the main spool was shifted to maximum displacement and then closed.
At the maximum displacement of the spool a pressure peak of 250 bar was created so as to excite the bridge pressure to force the piston check assembly to mechanically close the pressure compensator.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
3. Effect of Load Sensing Pressure Test:
134
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A and then the current brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool.
The displacement of the pressure compensator was studied as the main spool was shifted to maximum displacement and then closed.
At the maximum displacement of the spool the ball valve was quickly closed and opened to create an instantaneous pressure rise in the LS chamber. This pressure rise would cause the Pressure Compensator to close to adjust its pressure according to the pump pressure and the piston check would return to its home position..
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
Figure 6.35: DPX 100 – I slice and ball valve to close LS line
135 Figure 6.36: Physical layout of Figure 6.35
6.5.2 Functioning of the MVP 60 and DPX 100 Single Slice with LS feedback
Table. 6.7 Features of sensors and main elements of the apparatus used in the present research
Sensor Type Main features
M Prime mover ABB®, 4-quadrant electric
motor, 75 Kw
P Pump CASAPPA® MVP60, 84 cm3/r
P1 Strain gage WIKA®, Scale: 0..40 bar,
0.25% FS accuracy P2 – P3 – P4 – P5 –
P6 – P7– P8 Strain gage WIKA®, Scale 0..400 bar, 0.25% FS accuracy
Q2 Flow meter
VSE® VS1, Scale 0.05..80 l/min, 0.3% measured value
accuracy
T Torque/speed meter
HBM® T, Scale: 0..500 Nm, 12000 r/min Limit Velocity,
0.05 Accuracy Class
Θ Incremental encoder
HEIDENHAIN® ERN120, 3600 imp./r, 4000 r/min Limit velocity, 1/20 period accuracy LVDT Linear variable differential
transformer Magnet Schuz AVAX 015
136 The figure represents the schematic of the test setup that was developed to test the functioning of the MVP60 and DPX 100 single slice working together. The test was carried out by connecting the LS line from the valve block to the pumps flow compensator.
To prevent the LS line from saturating a 0.75mm bleed off orifice was integrated into the line. This helped the system dynamics by preventing saturation of the LS line and ensuring that there was no delayed response in the reaction of the pump owing to the time taken to drain out of the orifice within the flow compensator. A flow meter was set at the inlet of the valve and a pressure transducer to determine the inlet system pressure. The main spool was actuated by setting a pilot pressure of 35 bar with the gear pump following which the current to the proportional flow control solenoids were altered to displace the main spool.
The following tests were carried out on the pump and valve single slice combination:
1. Spool Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A and then the current brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool and the variation of the swash angle on the pump.
The displacement of the valves pressure compensator and the pumps flow compensator was studied as the main spool was shifted to maximum displacement and then closed.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
2. Pressure Compensator and Piston Check Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A and then the current brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool and the pumps swash angle was monitored.
137
The displacement of the pressure compensator was studied as the main spool was shifted to maximum displacement and then closed as well as that of the pump’s flow compensator.
At the maximum displacement of the spool a pressure peak of 250 bar was created so as to excite the bridge pressure to force the piston check assembly to mechanically close the pressure compensator.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
Figure 6.37: Pump and DPX 100 1 slice working together
138 Figure 6.38: Pump and valve block mounted on the test bench for combined operation
6.5.3. Functioning of the MVP 60 and DPX 100 Dual Slice with LS feedback
Table. 6.8. Features of sensors and main elements of the apparatus used in the present research
Sensor Type Main features
M Prime mover ABB®, 4-quadrant electric
motor, 75 Kw
P Pump CASAPPA® MVP60, 84 cm3/r
P1 Strain gage WIKA®, Scale: 0..40 bar,
0.25% FS accuracy P2 – P3 – P4 – P5 –
P6 – P7– P8 Strain gage WIKA®, Scale 0..400 bar, 0.25% FS accuracy
Q2 Flow meter
VSE® VS1, Scale 0.05..80 l/min, 0.3% measured value
accuracy
T Torque/speed meter
HBM® T, Scale: 0..500 Nm, 12000 r/min Limit Velocity,
0.05 Accuracy Class
Θ Incremental encoder
HEIDENHAIN® ERN120, 3600 imp./r, 4000 r/min Limit velocity, 1/20 period accuracy LVDT Linear variable differential
transformer Magnet Schuz AVAX 015
139 The figure represents the schematic of the test setup that was developed to test the functioning of the MVP60 and DPX 100 dual slice working together. The test was carried out by connecting the LS line from the valve blocks to the pumps flow compensator. To prevent the LS line from saturating a 0.75mm bleed off orifice was integrated into the line.
This helped the system dynamics by preventing saturation of the LS line and ensuring that there was no delayed response in the reaction of the pump owing to the time taken to drain out of the orifice within the flow compensator. A flow meter was set at the inlet of the valve and a pressure transducer to determine the inlet system pressure. The main spool was actuated by setting a pilot pressure of 35 bar with the gear pump following which the current to the proportional flow control solenoids were altered to displace the main spool.
The following tests were carried out on the pump and valve single slice combination:
1. Spool Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A of the first slice and simultaneously port B of the second slice, both slices were then brought back to zero.
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spools and the variation of the swash angle on the pump.
The displacement of the valves pressure compensator and the pumps flow compensator was studied as the main spool was shifted to maximum displacement and then closed.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
2. Pressure Compensator and Piston Check Displacement:
The current to the solenoids were linearly increased to a maximum current of 1.2 A to actuate port A of the first slice and simultaneously port B of the second slice, both slices were then brought back to zero.
140
During the course of the rise in current the spool displacement was monitored using the LVDT mounted on the main spool and the pumps swash angle was monitored.
The displacement of the pressure compensator was studied as the main spool was shifted to maximum displacement and then closed as well as that of the pump’s flow compensator.
At the maximum displacement of the spool a pressure peak of 250 bar was created so as to excite the bridge pressure to force the piston check assembly to mechanically close the pressure compensator.
The flow and pressure out of port A was measured during the course of the test.
The same test was repeated for Port B
Figure 6.39: DPX 100 – 2 slices
141