Rexroth proportional relief valve 3DREP6C-2X/25EG24N9K4

Brand

REXROTH/German Rexroth

Rexroth Solenoid Valves, Rexroth Piston Pumps, Rexroth Relief Valves, Rexroth Proportional Valves, Rexroth Vane Pumps

Main Functions of Rexroth Proportional Relief Valves:

Constant Pressure Relief: In a fixed displacement pump throttling system, the pump provides a constant flow rate. When system pressure increases, the flow demand decreases. The relief valve opens, allowing excess flow to return to the tank, ensuring a constant inlet pressure (i.e., pump outlet pressure) (the valve opening fluctuates with pressure).

Pressure Stabilization: Connected in series in the return oil line, the relief valve generates back pressure, increasing the smoothness of moving parts.

System Unloading: A small-flow solenoid valve is connected in series to the remote control port of the relief valve. When the solenoid is energized, the remote control port connects to the tank, unloading the hydraulic pump. The relief valve then functions as an unloading valve.

Safety Protection: The valve is closed during normal system operation. The relief valve opens only when the load exceeds the specified limit (system pressure exceeds the set pressure) to provide overload protection and prevent further pressure increase (typically, the set pressure of the relief valve is 10%–20% higher than the system's maximum working pressure).

In practical applications, it is generally used as a unloading valve, a remote pressure regulating valve, a high/low pressure multi-stage control valve, a sequence valve, and to generate back pressure (connected in series in the return oil line).

Relief valves generally have two structures: 1. Direct-acting relief valve. 2. Pilot-operated relief valve.

The main requirements for relief valves are: large pressure regulation range, small pressure regulation deviation, small pressure fluctuation, sensitive operation, large overload capacity, and low noise.

Rexroth proportional relief valve operating precautions:

Rexroth proportional relief valve noise and vibration

Components in hydraulic systems that are prone to noise are generally considered to be pumps and valves, with relief valves and solenoid directional valves being the main types of valves. Many factors contribute to noise generation. Relief valve noise includes both flow velocity noise and mechanical noise. The flow velocity noise is mainly caused by oil vibration, cavitation, and hydraulic shock. The mechanical noise is mainly caused by the impact and friction of parts in the valve.

(1) Noise caused by uneven pressure

The pilot valve section of the pilot-operated relief valve is a vibration-prone part, as shown in Figure 3. During high-pressure relief, the axial opening of the pilot valve is very small, only 0.003–0.006 cm. The flow area is very small, and the flow velocity is very high, reaching 200 m/s, which easily causes uneven pressure distribution, resulting in an imbalance of radial force in the cone valve and vibration. In addition, the ellipticity generated during the machining of the cone valve and cone valve seat, dirt adhering to the pilot valve port, and deformation of the pressure regulating spring can also cause vibration of the cone valve. Therefore, the pilot valve is generally considered to be the source of noise. The presence of elastic elements (springs) and moving mass (cone valves) creates conditions for oscillation. The pilot valve's front chamber also acts as a resonant cavity. Therefore, vibration of the cone valve easily causes resonance throughout the valve, generating noise. This noise is usually accompanied by severe pressure fluctuations.

(2) Noise from cavitation

When air is drawn into the oil for various reasons, or when the oil pressure is lower than atmospheric pressure, some of the dissolved air in the oil will precipitate, forming bubbles. These bubbles are larger in low-pressure areas, but when they flow with the oil to high-pressure areas, they are compressed, causing their volume to suddenly decrease or the bubbles to disappear. Conversely, if the volume is initially smaller in high-pressure areas, it suddenly increases when flowing to low-pressure areas. This rapid change in bubble volume generates noise, and because this process occurs instantaneously, it causes localized hydraulic shocks, resulting in vibration. The pilot valve port and main valve port of a pilot-operated relief valve experience significant changes in oil flow rate and pressure, making cavitation easy to occur, thus generating noise and vibration. (3) Noise from Hydraulic Shock

When a pilot-operated relief valve is unloaded, pressure shock noise occurs due to the rapid drop in pressure in the hydraulic circuit. The higher the pressure and capacity of the operating conditions, the greater this shock noise. This is because the unloading time of the relief valve is very short, resulting in hydraulic shock. During unloading, the oil flow rate changes drastically, causing a sudden pressure change and creating a pressure wave impact. The pressure wave is a small shock wave, generating very little noise itself. However, as it travels through the system with the oil, if it resonates with any mechanical part, it can increase vibration and amplify noise. Therefore, hydraulic shock noise is usually accompanied by system vibration.

(4) Mechanical Noise

The mechanical noise emitted by a pilot-operated relief valve generally comes from the impact of parts and friction caused by machining errors.

Sometimes, the noise emitted by a pilot-operated relief valve includes high-frequency mechanical vibration, generally referred to as self-excited vibration. This is the sound produced by the high-frequency vibration of the main valve and the pilot valve. Its occurrence rate is related to factors such as the configuration of the return oil pipeline, flow rate, pressure, and oil temperature (viscosity). Generally, smaller pipeline diameter, lower flow rate, higher pressure, and lower oil viscosity result in a higher incidence of self-excited vibration.

Rexroth proportional relief valve

0811 404 043 4WRPH6C3B25P-2X/G24Z4/M

0811 404 044 4WRPH6C3B40P-2X/G24Z4/M

0811 404 046 4WRPH6C4B40P-2X/G24Z4/M

0811 404 058 4WRPH10C3B50L-2X/G24Z4/M

0811 404 059 4WRPH10C3B100L-2X/G24Z4/M

0811 404 061 4WRPH10C4B100L-2X/G24Z4/M

0811 404 062 4WRPH10C3B50P-2X/G24Z4/M

0811 402 076 DBEBE6X-1X/315G24K31A1M

0811 402 075 DBETBEX-1X/180G24K31F1M

0811 402 074 DBETBEX-1X/315G24K0B5M

0811 402 073 DBETBEX-1X/250G24K31A1M

0811 402 072 DBETBEX-1X/80G24K31A1M

0811 402 071 DBETBEX-1X/180G24K31A1M

0811 402 070 DBETBEX-1X/315G24K31A1M

0811 402 063 DREB6X-1X/175MG24-25Z4V

0811 402 060 DRE6X-1X/175MG24-8NZ4M

0811 402 059 DRE6X-1X/75MG24-8NZ4M

0811 402 058 DRE6X-1X/310MG24-8NZ4M

0811 402 057 DRE6X-1X/245MG24-8NZ4M-6

0811 402 056DRUCKREGELVENTIL

0811 402 055 DRE6X-1X/175MG24-8NZ4M

0811 402 054 DRE6X-1X/75MG24-8NZ4M-7

0811 402 053DRUCKREGELVENTIL

0811 402 052 DREB6X-1X/310MG24-25Z4M

0811 402 051 DREB6X-1X/175MG24-25Z4M

0811 402 050 DREB6X-1X/75MG24-25Z4M

0811 402 045 DBE6X-1X/80G24-8NZ4M

0811 402 044 DBE6X-1X/180G24-8NZ4M

0811 402 043 DBE6X-1X/315G24-8NZ4M

0811 402 042 DBE6X-1X/315G24-25NZ4M

0811 402 041 DBE6X-1X/180G24-25NZ4M

0811 402 040 DBE6X-1X/80G24-25NZ4M

0811 402 039 DBETX-1X/180G24-25NZ4M-36

0811 402 038 DBETX-1X/25G24-25NZ4M-36

0811 402 037 DBETX-1X/350G24-25NZ4M

0811 402 036 DBETX-1X/50G24-8NZ4M

0811 402 028 DBETX-1X/250G24-8NZ4M-34

0811 402 027 DBETX-1X/250G24-8NZ4M-35

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0811 402 020 DBETFX-1X/315G24-27NZ4M

0811 402 013 DBETBX-1X/28G24-37Z4M

0811 402 012 LFR25DBE137-1X/

0811 402 011 DBETBX-1X/25G24-16Z4M

0811 402 009 VORSTEUERVENTIL

0811 402 008 VORSTEUERVENTIL

0811 402 007 DBETBX-1X/80G24-37Z4M-38

0811 402 005 DBETBX-1X/315G24-37Z4M-38

0811 402 004 DBETBX-1X/315G24-37Z4M

0811 402 001 DBETBX-1X/250G24-37Z4M-38

0811 404 800 4WRPEH10C3B50L-2X/G24K0/A1M

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