182 From Figure relating to the bode plot of the destroking of the pump we can clearly see that the pump has a maximum response frequency of 3.5 Hz for destroking the pump, after which the pump goes out of phase. At 3 Hz we see that the pump is - 60 Degrees out of phase. After this value this frequency there is a change in the amplitude so the pump cannot be used for operations requiring frequencies higher than 3 Hz.
From Figure relating to the bode plot of the stroking of the pump we can clearly see that the pump has a maximum response frequency of 1.8 Hz for stroking the pump, after which the pump goes out of phase. At 2 Hz we see that the pump is - 106 Degrees out of phase.
After this value this frequency there is a change in the amplitude so the pump cannot be used for operations requiring frequencies higher than 3 Hz.
The data presented in this chapter is purely experimental to gain a better idea of the maximum frequency capacities of the pump. Future work could include modifying the linear equation of the pump model to replicate these high frequency tests. Though it might not be necessary as excavator response is generally less than 0.5 Hz.
183 into the valve block defined as the system pressure which is modeled as an ideal flow element reading data from the actual experimental flow of the test bench. A relief valve has been used to set the inlet system pressure. The relief valve model used in Figure is that of an ideal relief valve to replicate the relief valve that was used to set the maximum system pressure of the test setup. The pressures of work port A and B were derived from the test bench and were directly fed to the simulation model using data table controllable relief valves. The main spools displacement was directly driven by a displacement transducer that read the data table from the experimnet on the main spools position and used the data to move the spool accordingly.
Figure 7.30: Model validation setup with test bench inputs in the AMESim environment
184 7.3.1.Test of a DPX 100 Single slice
1. Test 1 Analysis of Results:
The spools displacement as it can be seen the motion of the spool in the direction of Port A is more controlled as against the control in direction Port B. This is due to the different PWM settings on the controllers used to control the proportional solenoid
The system pressure defines the variation of the system pressure during the course of the experiment as the main spool opens and closes.
The bridge pressure provides insight into the pressures available to the work ports and conditions where the piston check valve is closing due to the increase in bridge pressure in respect to system pressure.
Port A pressure describes the pressure characteristics of the utility port as the load is controlled by the test benches relief valve.
Port A flow compares the experimental and simulation flow characteristics of the flow out of the valve as it can be seen there is a good correlation between the comparisons of results.
Port B pressure describes the pressure characteristics of the utility port as the load is controlled by the test benches relief valve.
Port B flow compares the experimental and simulation flow characteristics of the flow out of the valve as it can be seen there is a good correlation between the comparisons of results.
185 Figure 7.31 a: Main Spool Displacement
Figure 7.31 b: System Pressure
Figure 7.31 c: Bridge Pressure
186 Figure 7.31 d: Port A Pressure Characteristics
Figure 7.31 e: Port A Flow characteristics
Figure 7.31 f: Port B Pressure Characteristics
187 Figure 7.31g: Port B Flow characteristics
7.3.2 Test 2 DPX 100
2. Test 2 Analysis of Results:
The spools displacement as it can be seen the motion of the spool in the direction of Port A is more controlled as against the control in direction Port B. This is due to the different PWM settings on the controllers used to control the proportional solenoid
The system pressure defines the variation of the system pressure during the course of the experiment as the main spool opens and closes.
The bridge pressure provides insight into the pressures available to the work ports and conditions where the piston check valve is closing due to the increase in bridge pressure in respect to system pressure.
Port A pressure describes the pressure characteristics of the utility port as the load is controlled by the test benches relief valve.
Port A flow compares the experimental and simulation flow characteristics of the flow out of the valve as it can be seen there is a good correlation between the comparisons of results.
Port B pressure describes the pressure characteristics of the utility port as the load is controlled by the test benches relief valve.
188
Port B flow compares the experimental and simulation flow characteristics of the flow out of the valve as it can be seen there is a good correlation between the comparisons of results.
Figure 7.32 a: Main Spool Displacement
Figure 7.32 b: System Pressure
189 Figure 7.32 c: Compensator Displacement
Figure 7.32 d: Bridge Pressure
Figure 7.32 e: Port A Pressure
190 Figure 7.32 f: Port A Flow
Figure 7.32 g: Port B Pressure
Figure 7.32 h: Port B Flow
191