Here are two methods used to prevent the idle pump from motoring in a hydraulic steering gear system:
1. Pressure Relief Valve:
- Function: A pressure relief valve is a mechanical safety device installed within the hydraulic circuit. It remains closed when the system pressure is below a preset threshold.
- Operation: As the hydraulic pump continuously pressurizes the fluid, the pressure builds up in the system. Once the pressure reaches the relief valve’s setting, the valve opens.
- Preventing Idle Pump Motoring: When the steering gear is not in operation, and the rudder isn’t being moved, the pressure in the system remains low. The pressure relief valve stays closed, allowing fluid to return to the reservoir through the bypass passage within the valve. This prevents the pump from unnecessarily churning fluid and wasting energy.
- Benefits: Simple and reliable method, easy to integrate into existing systems.
- Drawbacks: May lead to slight pressure fluctuations as the valve opens and closes, potentially affecting steering responsiveness.
2. Load Sensing Pump:
- Function: A load sensing pump is a more advanced type of hydraulic pump that adjusts its output flow based on the system’s actual demand.
- Operation: The pump continuously monitors the system pressure through a sensor. When the pressure rises due to a demand for hydraulic power (e.g., moving the rudder), the pump automatically increases its flow rate to meet that demand.
- Preventing Idle Pump Motoring: When there’s no demand for hydraulic power (rudder not moving), the system pressure remains low. The load sensing pump detects this low pressure and automatically reduces its flow to a minimum, or even stops completely in some designs. This eliminates unnecessary churning of fluid by the pump during idle periods.
- Benefits: More efficient operation, reduces energy consumption and heat generation in the system.
- Drawbacks: More complex and expensive compared to pressure relief valves. May require additional sensors and control systems.
Choosing the Right Method:
The selection between a pressure relief valve and a load sensing pump depends on several factors, including:
- System Complexity: For simpler systems, a pressure relief valve might be sufficient.
- Performance Requirements: If precise control and energy efficiency are crucial, a load sensing pump could be a better choice.
- Cost Considerations: Pressure relief valves are generally less expensive than load sensing pumps.
By implementing one of these methods, the hydraulic system ensures that the pump doesn’t waste energy by motoring when the steering gear is not in use.