Hydro Motor Case Study

the second stage starts. In this stage that is in secondary controlled mode of operation of the drive, an increase of the vehicle speed is achieved by reducing the displacement setting of the hydro-motor. A schematic representation of the pump and the motor displacement control is shown in Fig. 1. Fig. 1 Standard speed control

By choosing the control parameter settings, it is possible to run the transmission at optimum energy settings.

The present study deals with the steady state performance analysis of a closed circuit hydrostatic drive used in HEMM. Both primary and secondary controlled mode of operations of the system is considered to cover wide torque and speed range. System model [14,15] is made using Bondgraph technique. From the

4. It consists of seven numbers of pistons which are arranged in a circular pattern at regular intervals and reciprocate inside a cylinder block. With the rotation of the cylinder block, when the pistons cross over the inlet port, they are withdrawn from the cylinder block and fluid flows into the piston bore. When the pistons passes over the delivery port, it move forward into the cylinder block and the hydraulic fluid is forced out of the piston bore. As the inclination of the swash plate (α) is varied, the piston stroke (Hk) changes and so does the quantity of fluid piston

The fluid flows through the gap due to a pressure difference. Various leakage path of the pump and the hydro-motor considered for the analysis are shown in Figs. 3 and 4. They are as follows:

a) Gap across the piston and the barrel hole (Qal).

b) Gap across the ball and socket joint (Qs).

c) Gap across the valve plate and cylindrical barrel (Qd).

Combining the above leakages, they are accounted as external leakage resistances in the model.

d) Inter-port leakages (Qilp and Qilm) of the pump and the hydro-motor are considered as internal leakage resistance.

3. Modelling of the system The dynamic analysis of any physical system using bondgraph simulation method [14, 15] is an established tool. Bondgraph is a representation of power flow and, as such, it constitutes a very useful approach in formulating descriptive equations for a physical system. For a brief representation of a physical system consisting of morphologically similar sub-systems, multi-bondgrph is used. The displacement chambers of the multi-piston pump and the hydro-motor experience compression and expansion phases sequentially. The multi-bondgraph model of the closed circuit hydrostatic drive is shown in Fig.