Valves (Yuken)
(This document was written at the time when the lab had only the supine apparatus. Hence, reference to the "Forward Flow" valve is actually to the "Fwd Flow 1" valve in the current setup. The "servo-valve" refers to the one on the supine setup.)
There are two Yuken valves (Pressure valve: DSWG-03-2B2-A120-1090 and Forward Flow valve: DSG-03-2B2-A120-5090) controlling the flow to the servo-valve. The Yuken valves are two-position solenoid operated directional valves with a spring-offset spool.
To understand how the schematics of these valves are drawn, first look at the valve from the front. In this position, solenoid B is on the left and solenoid A is on the right. Since our valves are for two positions only, there is only one solenoid operating at a time. When solenoid B is mounted (as in FFlow valve), the schematic for the standard mounting is to be followed. When solenoid A is mounted (as is our Pressure valve), the reverse mounting schematic is the correct one. On the schematic, the default position for these valves is the box furthest from the solenoid since when the solenoid is activated, it pushes the spool out (and therefore pushes the box closest to it to the active box). The active box is the one with the labels (A,B,P,T) marked on it.
The valves are mounted on a subplate (DSGM-03Y-2190), which connects the valve to the hydraulic pipes. The base of the valve is labeled with 5 letters and these correspond to the passages that connect the valve to the top of the subplate. There are 4 holes (not five) in an inverted checkmark pattern on the top of the subplate since one of the tank passages (T) is always blocked. These 4 holes come out of the bottom of the subplate in a diamond shaped pattern and are not labeled so you need to see the schematic of the underside of the subplate to see what pipes are connected to what passages. One of the holes on the bottom of the subplate is blocked since this is a two-position valve.
Here is a summary of what happens when each switch is turned on to operate the actuator.
|
Switch on |
Pressure Valve |
FFlow Valve |
What the system is doing |
||
|
state |
flow |
state |
Flow |
||
|
Pump |
default |
P to B |
Default |
B to T |
Circulating the fluid from the tank back to the tank |
|
Pressure |
Solenoid a active |
P to A |
Default |
B to T |
Building up pressure in the accumulator |
|
Forward Flow |
Solenoid a active |
P to A |
Solenoid b active |
P to B |
Pushing fluid to the servo-valve (and actuator) |
Last Modified: November 1, 2001 Laura Galiana