Blain hydraulic lift drives

In standard hydraulic drives, the pump is always running at full speed. The flow of oil and thus the motion of the cage is managed solely via the control valve. The valve and the required valve electronics can be relatively complex. The bypass control in the valve causes the oil to heat significantly, which reduces its useful life, may necessitate oil coolers and has a negative impact on ride quality. The effect of the oil temperature on the ride quality means that valve adjustments are often required at different times of the year. The energy efficiency of these systems barely meets today’s standards.

An important and logical step on the way to energy-efficient drive concepts for hydraulic lifts is, therefore, the use of modern inverter drives. The key advantages of these systems are the decreased motor capacity requirements, reduced energy consumption and the precise, smooth ride, even with heavy loads.

Up until now, however, these benefits were countered by several disadvantages: For example, the initial investments for these systems are quite high, as are the planning and maintenance requirements. In addition, hydraulic lifts with inverters use more energy during idle than their conventional counterparts. As a result, inverter drives are now used only for hydraulic lifts designed for particularly heavy loads. According to current estimates, the figure is around 20%*. New technical developments are expanding the potential area of application for energy-efficient solutions with inverter drives. However, two opposing methods have turned out to be dead-ends, the first of which was to reduce the complexity at the cost of performance. The second approach was to improve the ride quality and efficiency by using increasingly complicated additional components such as sensors or encoders, which make the system complex, more prone to failure and difficult for non-experts to operate.

The VVVF (Variable Voltage Variable Frequency) solution developed by Blain Hydraulics and Yaskawa demonstrates the actual potential for optimization, which can be found in the inverter drive technology itself and in the valve of the control unit. With this solution, the effective area of application for inverter drives covers approximately 70% of the world’s hydraulic lifts in residential buildings with motor capacities up to 15 kW internationally and around 80% of those in Europe. The energy-efficient package solution comprises the new EV4 hydraulic control valve from Blain and the new L1000H inverter drive from Yaskawa. Both the valves and the inverter drive are available in various sizes and designs.
The motor is controlled without an encoder (open-loop). A speed sensor, which is normally mounted directly on the motor in the tank and thus constitutes a major cost factor, is not required. This not only simplifies the system, but also makes the solution particularly attractive when renovating existing power units.
Further advantages of the new concept: The system merely requires a sensor to record the oil temperature. Based on the measured value, all negative effects on the ride quality resulting from a varying oil temperature can be compensated. The overheat sensor is easy to install and relatively durable, which greatly increases the reliability of the system. Unlike those used in previous systems with inverter drives, this sensor does not require any additional pressure sensors or flow meters. The valve is actuated directly via the lift control system, which eliminates the need for elaborate valve controls that are not only prone to failure but also require a great deal of time to set. As a result, even existing control valves can be replaced relatively easily with a new EV4. Existing mechanical valves from Blain can be retrofitted as fully valid EV4s and combined with an L1000H. The power unit and control system can continue to be used.