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Motor-type flow divider as an intensifier
A motor-type flow divider intensifies pressure at one outlet when the other outlet is at a lower or no pressure. In the case of a 2-outlet motor flow divider with equal displacements, when inlet pressure is 1000 psi, one outlet can be at 2000 psi while the other outlet is 0 psi. While pressure doubles, flow from the intensified outlet is one half that at the inlet. The energy from the zero outlet motor transfers to the other motor to produce intensified pressure.
With more than one section going to tank, say from a 4-outlet divider with three outlets to tank, intensification would be four times. While the intensified fluid is four times inlet pressure, volume is only one-fourth inlet flow.
Using motor dividers with unequal sections is another way to get high intensification. If the motor in one section discharges 3 gpm to tank and the other section sends 1 gpm, intensification is still 4:1.
Figures 13-22 through 25 show how to use this feature of motor-type flow dividers in a circuit. This circuit has equal flow divider C and 3-way directional valve D in the cylinder cap end line. In the at-rest condition, both outlets of the flow divider connect to the cap-end port.
In Figure 13-23, the cylinder is extending at full speed and low thrust. Shifting solenoid A1 of the directional valve ports oil through one side of the divider and 3-way valve to the rod-end port. Fluid from the other side of the divider goes directly to the cylinder rod-end port. Size the pump and valves to provide enough flow for the speed required in the fast-forward portion of the cycle. Normally, motor horsepower is low for a cylinder moving a light load.
When the cylinder makes a limit switch, as in Figure 13-24, it energizes solenoid C1 on the 3-way valve. When the valve shifts, oil from one section of the motor flow divider goes to tank. Pressure doubles, while cylinder speed drops to half what it was before energizing solenoid C1.
This circuit works best on actuators that do not stall. Using this setup for a fast advance and clamping operation might result in excess heat from internal leakage in the flow divider during the clamping part of the cycle.
Energizing solenoid B1, Figure 13-25, makes the cylinder retract. Oil from the cap-end port flows through both sections of the flow divider, then back to tank through the directional valve.
When using a motor-type flow divider as an intensifier, make sure it is capable of operating at the elevated pressure. Pressure rating of an inexpensive gear motor flow dividers may be only 2000 psi intermittent and 1500 psi continuous. Some gerotor flow dividers go as high as 4500 psi intermittent and 3000 psi continuous.