1. The power domain (working limit) of the proportional valve
For the direct-acting electro-hydraulic proportional throttle valve, because the hydraulic force acting on the valve core is proportional to the flow rate and flow rate (pressure) through the valve port, when the working condition of the electro-hydraulic proportional throttle valve exceeds the area range (called the power domain or working limit) of the product of its pressure drop and flow rate, that is, the power representation, the hydraulic force acting on the valve core can be increased to the extent equivalent to the electromagnetic force, making the valve core uncontrollable. Similarly, there are power domain issues with direct-acting electro-hydraulic proportional directional valves. When the pressure drop across the valve port of the electro-hydraulic proportional directional valve increases, the flow through the valve port increases, and the hydraulic force in the opposite direction of the electromagnetic force of the proportional solenoid increases. When the opening and pressure drop of the valve port reach a certain value, with the increase of the pressure drop of the valve port, the influence of the hydraulic force will exceed the electromagnetic force, resulting in the decrease of the opening of the valve port, and finally the flow rate of the valve port is not only not increased but decreased, which is the concept of the power domain of the electro-hydraulic proportional directional valve. When choosing a proportional throttle valve or proportional directional valve, it is important to note that the power domain of the electrohydraulic proportional throttle valve or proportional directional valve cannot be exceeded.
2. Pollution control
The pollution degree of proportional valve to the oil is usually required to be 7, 8 and 9 of NAS638 (16/13, 17/14, 18/15 of IS0), and the main link to determine this index is the pilot stage. Although electro-hydraulic proportional valves are more resistant to pollution than servo valves, oil contamination should not be taken lightly, because many failures in electro-hydraulic proportional control systems are also caused by oil pollution.
3. Matching and placement of proportional valve and amplifier
The proportional valve must be matched with the amplifier. Usually proportional amplifiers can be supplied with proportional valves, and the amplifiers generally have negative feedback of depth current and flutter current superimposed on the signal current. The amplifier is designed to keep the spool in its original position or to keep the system pressure lowest in the event of a power failure or differential transformer disconnection for safety. A ramp signal generator is sometimes set up in the amplifier to control the boost and buck times or the acceleration or deceleration of the motion. Amplifiers that drive proportional directional valves often also have function generators to compensate for the relatively large dead zone characteristics. The distance between the proportional valve and the proportional amplifier can be up to 60m, and the distance between the signal source and the amplifier can be arbitrary.
4. Traditional methods of controlling acceleration and deceleration
The traditional methods of controlling acceleration and deceleration are: reversing valve switching time delay, hydraulic cylinder inner end position buffering, electronically controlled flow valve and variable pump. A good solution can be provided with proportional directional valves and ramp signal generators, which can increase the cycle speed of the machine and prevent inertial shocks.
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Rexroth hydraulic motor balancing valve
The hydraulic motor is fixedly connected to the housing, and the oil propulsion rotor entering from the port rotates around a central point. This slow-rotating rotor drives the output through a splined shaft called a cycloidal hydraulic motor. After the advent of this early cycloid motor, through decades of evolution, another concept of horse ...
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Rexroth launches the new linear module SMS
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● Optional compact motor accessories
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The new linear axes are suitable for handling cost-sensitive small parts and can be used as an alternative to complex pneumatic solutions. (Image source: Bosch Rexroth Co., Ltd.)
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What causes Rexroth hydraulic pumps to heat up?
1. Poor assembly of Rexroth hydraulic pump leads to abnormal heating of the hydraulic pump
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Analysis of abnormal heating fault of vane pump:
1. The oil temperature is too high 2. The oil cat degree is too large and the internal leakage is too large
3. The working pressure is too high
4. The oil return port is directly connected to the pump population
Abnormal heating elimination method of vane pump:
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There are three main types of hydraulic pumps: gear pumps, vane pumps and piston pumps.
1. Gear pump:
Advantages: small size, simple structure, less strict requirements for the cleanliness of the oil, and cheaper price;
Defects: However, the pump shaft is subject to unbalanced force, serious wear, and leakage.
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Disassembly and cleaning steps for Rexroth hydraulic valves
(1) Disassembly. For hydraulic valves, although most of the parts are connected by bolts, the hydraulic valve is not disassembled when designed, and if it is forcibly disassembled due to lack of special equipment or lack of professional technology, it may lead to damage to the hydraulic valve. ...
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What are the common faults of Rexroth servo motors?
1. Aging of circuit board components: The components in the Rexroth servo motor circuit board may have problems such as aging and damage as the use time increases, resulting in the circuit board not working normally.
2. Poor circuit board contact: Rexroth servo motor circuit board is connected with other equipment.
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How to adjust the DFR on the Rexroth A10VSO piston pump
Adjust the pressure adjustment screw of the relief valve to the loosest state.
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Rexroth at the Hannover Messe 2023
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Precautions for Rexroth pressure reducing valves
1. For easy operation and maintenance, the valve is generally installed upright on the horizontal pipeline.
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Rexroth Hydraulic Pumps – How Does a Hydraulic Pump Work?
In modern construction machinery, basically inseparable from hydraulic working devices, even if the main working devices do not use hydraulic equipment, usually need hydraulic systems to achieve some auxiliary work, hydraulic pressure is so important, and our life and work is very close.
Image
But...
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Common Causes and Troubleshooting Methods of Hydraulic Pumps(9-16)
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DAMBACH has developed a new shuttle system based on Rexroth's compact control system
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Tried and tested
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Basic understanding of Rexroth solenoid valves
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Rexroth launches ctrlX OS operating system for third-party hardware
Automation is even more open and free
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The causes and treatment methods of the unstable flow of Rexroth hydraulic pumps
1. Rexroth hydraulic pump has no flow rate.
In fact, this is broadly similar to the reason why Rexroth hydraulic pumps have no pressure as mentioned earlier. Here can be referred to by the explanation of the past period, and a few points can be added.
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Areas of application for Rexroth hydraulic pumps
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