Question

Name: Student No.: 1. The pump represented by the graph below has a displacement of 3 in /rev. Determine- (12 pts.) Efficiencies at 3000 psi - Overall efficiency (6) Volumetric Efficiency,% 100 90 1 - - - - 1 1 1 1 1 1 1 - - - 1 80 - - - - - 70 - - - EFFICIENCY, % 60 V 1 50 40 30 20 0 500 1000 2000 2500 3000 1500 SPEED, N (a) The volumetric efficiency (mv) for the pump at 1250 rpm (2 pts.) (b) The actual flow rate (in gpm) under these conditions (3 pts.) (c) The overall efficiency, n. (2 pts.) (d) The mechanical efficiency, Nm (2pts.) (e) Torque delivered to the pump (3 pts.) 2. Draw labeled sketch for wet armature solenoid. Describe how a wet armature solenoid works. (8)

Answer 1

Answer:

Given datas: Displacement is given as

N = 1250rpm

Pressure P = 3000psi

(a) Corrosponding to the 1250 rpm in the efficiency speed curve, we can get that

$\eta _{v}=82.5%$ Percent Answer

(b) Actual flow rate in gpm.

Actual flow rate for the pump can be given as

$Q_{A}=\eta _{v}\frac{V_{pN}}{231}$

Now putting all the values we will get

$Q_{A}=.825\left ( \frac{3*1250}{231} \right )$

Answer

(c) Corrosponding to 1250 rpm, Overall efficiency

$\eta _{o}=74$ Percent Answer

(d) Mechanical efficiency

$\eta _{o}=\eta _{v}\eta _{m}$

$\eta _{m}=\frac{\eta _{o}}{\eta _{v}}$

$\eta _{m}=\frac{.74}{.825}$

$\eta _{m}=.896$

$\eta _{m}=89.6 percent$

(e) Torque delivered to pump

$T=\left ( \frac{PV_{p}}{2\pi } \right )$

Now putting the values we will get

$T=\left ( \frac{3000*3}{2\pi } \right )$

(2) Wet armature solenoid labelled diagram:

Coir STATIC SEAL IRON CORE EZAE 1 - MANUAL OVERRIDG → ARMATURES OIL

Working of wet armeture solenoid

The wet armature solenoid design is more common when the complete armature assembly is submerged in the oil from the valve.The work can be explained as the solenoid magnetically moves the armature when there is presence of oil and it is submerged in the oil.

The design of wet armature solenoid is more feasible as there is very less leakage as there is no wearable dynamic seals are present. There is only one sealing available which is known as O ring and it seals the threaded connection between the bosy and the iron core and if some other sealing in case if present, the one which will be present on the manual override pushes the pin which is although a dynamic seal only but it acts when the valve is reset once in a while.

The advantage of this wet armature solenoid us that the movement of the full set up is dampened due to the oil. Due to this the operation is smooth, less wear so that longer life is acheived and also operation is very quite.But oil presence make the wet armature design for more 60% power to be actuated.

It can direct and stop the flow at any point in a hydraulic system with the help of control valve. The main function is to determine the direction of the flow.