Rover Group wanted to install a new facility which was to comprise of four individual test cells for full vehicle testing, a general purpose test area for sub assembly testing, a small rigs area for components testing and a safety test area for testing associated with passenger safety.
Savery Hydraulics was appointed to design and commission the electronically controlled hydraulic ring main system at Rover Group’s servo hydraulic test facility. The solution needed to maintain supply pressure within high tolerances, while operating with maximum economy.
Prior to the design and commission Savery worked with the Rover group to conduct a failure mode effect and critical analysis of the system, to minimise any potential problems which could have occurred during the design and commissioning phases.
The Hydraulic System
The pumping system was divided into 2 identical sections, each feeding into the ring main. In the event of major component failure such as a fluid reservoir the system remained operational. The ring main had strategically positioned isolation valves, which allowed sections to be taken out of service and the fluid diverted. System interlocks prevented pressurisation of return lines in isolated sections.
The fluid was routed around the facility in a 4” nominal bore pressure and return main. This fed isolation and depressurisation manifolds in each of the four test cells, seven in the general purpose test area and one in the small rigs and safety test area.
Five seal drain power packs were positioned around the facility to collect fluid from drain lines and pump the filtered fluid back into the return main.
The mains were supplied with the total maximum mean flow requirement of 2.280 l/min at 210bar from a purpose built pump house containing the two independent power systems. The systems were cross connected with isolating valves. Each was subdivided into multiple modules allowing routine servicing to be carried out without affecting system availability. Each power system comprised:
The Control System
The control system monitored and controlled the ring main system, minimising the need for human intervention, this comprised of:
The control system supplied the test cells using minimum power it did this by measuring the flow into the ring main and by deducing and running or loading the required number of pumps. At the same time, full pressure was maintained in the ring main. The life expectancy of the main pump modules was greatly extended as only the minimum number of pumps were run to meet the flow. The system took into account any pumps that were unavailable due to maintenance and if necessary limited the number of test cells in use. It was able to anticipate high instantaneous flows up to 1200 l/min and put the requisite number of pumps on standby.
Fault tracing was carried out at the PC using mimic screens of the hydraulic circuits of all system modules. A master status screen showed the current status of all test cells, ring main isolating valves etc, as well as numerical values for crucial flows, pressures, temperatures etc, at key points in the system. The system normally ran in automatic mode but could be switched to manual allowing the user to click switches on the screen with a mouse.