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DHZO
ATOS
The DHZO series is a high-performance direct-acting proportional directional valve. It integrates a proportional solenoid, valve core and valve body, position sensor, and electronic amplifier into one unit. Through the input electrical signal (analog or digital bus), it achieves continuous, precise, and stepless proportional control of the hydraulic oil flow direction and flow rate. It is the core control component of modern high-precision and high-dynamic response hydraulic systems.
This series of valves adopts a modular and integrated design, achieving a high degree of integration between hydraulic and electronic control. Its core is a four-way valve core that slides within a five-chamber valve body, driven directly by proportional electromagnets on both sides. Depending on the configuration, it is mainly divided into the following types:
• Basic type: without position sensors, providing directional and pressure-free compensation for flow control.
• Closed-loop control type: Equipped with integrated analog or digital electronic amplifiers and built-in displacement sensors (such as LVDT), it enables closed-loop feedback control of the valve core position, with superior accuracy and dynamic performance.
• High-performance type: Specifically designed for closed-loop control systems that demand extremely high dynamic response and accuracy. It typically employs positive cover valve cores and optimized control algorithms.
This series of valves complies with the ISO 4401 international installation interface standard and offers various diameter specifications (such as NG06, NG10, etc.) to meet the different system flow requirements.
The valve core displacement has a highly linear relationship with the input electrical signal (such as 0-10V or 4-20mA), enabling fine and continuous adjustment of the flow rate. The models with closed-loop control have high repeatability and small hysteresis, ensuring the consistency and repeatability of the control.
With optimized electromagnets and low-friction valve cores, it has a fast step response time and can closely track rapidly changing control instructions, meeting the demanding requirements of high-speed automation equipment.
The valve body is made of high-strength materials, with a high rated working pressure and the ability to withstand system peak pressure. Different diameter models offer a wide range of flow coverage, meeting the power requirements of from lightweight to heavy-duty equipment.
To overcome the speed fluctuations of the actuator caused by load changes, an external superimposed pressure compensation module can be easily connected. This function can maintain a constant valve port pressure difference, thereby achieving precise flow control independent of the load pressure (i.e., "load-sensitive" control).
The electromagnetic coils are made with full encapsulation technology, featuring high insulation levels. The overall design focuses on shock resistance, impact resistance, dustproof, and waterproof. The range of seal materials is wide, enabling adaptation to a wide temperature range (such as -40°C to +80°C) and various types of hydraulic fluids (mineral oil, HFC/HFD flame-retardant liquids, etc.).
Models with integrated digital amplifiers support parameter setting and diagnosis via USB and other interfaces, and can optionally be equipped with mainstream fieldbus interfaces such as PROFIBUS-DP, CANopen, and EtherCAT, facilitating seamless integration into industrial automation networks and PLC control systems for remote monitoring and intelligent maintenance.
With its precise electro-hydraulic proportional control capability, such valves are widely used in industries that have high precision and dynamic requirements for hydraulic power:
Controlling the hydraulic drives of robot joints to achieve high-precision and high-speed motion trajectory control.
Precisely control the mold closing, injection, and plasticization pressure and speed on injection molding machines and extrusion machines, thereby improving product quality and production efficiency.
Leading control systems for excavators, cranes, and pavers, enabling precise operation of the working devices and smooth, stepless speed regulation.
Controlling the hydraulic cylinders in rolling mills, presses, and continuous casting machines to achieve high-precision force and position control.
Achieve precise load and displacement closed-loop control on material testing machines, fatigue test benches, and simulation vibration platforms.
such as the pitch control system of wind turbines, and the steering and suspension systems of specialized vehicles.
Clearly define the maximum flow rate, system working pressure, and control accuracy requirements for the actuator.
Choose an open-loop type, analog closed-loop type, or digital bus type based on the complexity of the control.
Select the valve core position type (such as O-type, Y-type, etc.) according to the safety requirements of the system's position state, and choose an appropriate diameter based on the flow rate.
Ensure that the installation dimensions, oil port specifications, sealing materials are compatible with the existing system.
1. The surface of the installation base plate should be flat and clean, meeting the specified requirements for flatness and roughness.
2. In the system oil circuit, a high-pressure filter must be installed before the valve (typically recommended as 10μm or finer) to ensure the cleanliness of the oil.
3. Electrical connections should use shielded cables and be reliably grounded. The signal lines between the amplifier and the controller should be kept away from the power lines to reduce electromagnetic interference.
1. Regularly monitor the cleanliness and physical properties of the system oil, and replace the filter elements at the scheduled time.
2. Periodically check the zero position and gain of the valves using the accompanying software or equipment, and calibrate them if necessary.
3. Pay attention to the valve body temperature and ensure it operates within the specified working temperature range.
The DHZO series of hydraulic proportional directional solenoid valves represent the advanced level of electro-hydraulic proportional control technology. Through the deep integration of precise mechanical structure, high-performance electromagnetic drive and intelligent electronic control, it provides reliable, precise, responsive and easily-integrated fluid power control solutions for various industrial and mobile equipment. Whether it is a closed-loop servo system that pursues ultimate performance, or a scenario that requires cost-effective proportional control, this series can offer a variety of model options and is a key foundational component for building modern and intelligent hydraulic systems.
| Assembly position | Any position |
| Subplate surface finishing | Roughness index Ra 0,4 - flatness ratio 0,01/100 (ISO 1101) |
| Ambient temperature | -20°C ++70°C for -A execution; -20°C ++60°C for -AE execution |
| Fluid | Hydraulic oil as per DIN 51524 ... 535 for other fluids see section |
| Recommended viscosity | 15 +100 mm3/s at 40°C (ISO VG 15+100) |
| Fluid contamination class | ISO 4406 class 20/18/15 NAS 1638 class 9, in line filters of 10 um (ß10≥75 recommended) |
| Fluid temperature | -20°C +60C (standard seals) -20°C +80C (/PE seals) |
| Coil resistance R at 20C | 3+ 3.3 2 for standard 12 Voc coil; 2 + 2,2 2 for 6 Voc coil; 13 + 13,4 2 for 18 Voc coil |
| Max solenoid current | 2,6A for standard 12 Voc coil; 3,25A for 6 Voc coil; 1,5 A for 18 Voc coil |
| Max power | 40 Watt |
| Protection degree (CEI EN-60529) | IP65 for -A execution; IP67 for -AE execution, (see sect. 7 |
| Duty factor | Continuous rating (ED=100%) |
A1: The DHZO series is a direct-acting electro-hydraulic proportional directional control valve. The key difference lies in the control method:
There are only two states, "open" or "close", controlling the flow path connection or disconnection, but unable to adjust the flow rate.
Receives continuous analog electrical signals (such as 0-10V or 4-20mA), and proportionally controls the displacement of the valve core, thereby enabling continuous and stepless regulation of the hydraulic oil flow direction and flow rate. This means that you can precisely control the movement speed and direction of hydraulic actuators (cylinders, motors) just like using an "accelerator".
A2: The pressure compensation function is crucial for ensuring the accuracy of flow control. According to the flow formula Q = K·√ΔP, the flow rate through the valve not only depends on the valve opening (determined by the electrical signal), but is also affected by the pressure difference (ΔP) before and after the valve. Changes in load will cause fluctuations in pressure difference, thereby resulting in fluctuations in flow rate.
When the load becomes heavier, the actuator speed will slow down; when the load becomes lighter, the speed will increase.
This feature automatically maintains a constant valve port pressure difference through an internal or external compensator (such as a differential pressure reducing valve or a differential pressure relief valve). Thus, the flow is solely determined by the input signal and is independent of load pressure fluctuations, thereby achieving precise and stable speed control.
A3: "Direct-acting" means that the proportional electromagnet directly drives the movement of the valve core.
• Advantages:
It eliminates complex structures such as the pilot stage, has fewer leakage points, and has relatively strong anti-pollution capability.
The electromagnetic coil directly operates, and the step response time usually reaches 15-25 milliseconds, which is suitable for scenarios requiring rapid response.
It can work normally even when the system pressure is low.
• Disadvantages:
The driving force is limited: Due to the electromagnetic force limitation, it is usually used in situations with smaller diameters (such as NG06, NG10) and medium flow rates. For large flow applications, pilot-operated proportional valves are typically used.
A4: The model code usually contains information about the series, function, diameter and mechanism:
• DHZO: represents the digital proportional directional valve series.
• A: Represents the basic type, without an integrated electronic amplifier. If it is AE or AES, it indicates the presence of an integrated analog or digital amplifier.
• 071: Thread code, corresponding to the nominal diameter (for example, 07 represents approximately 6mm), and related to the rated flow rate (for instance, 70 L/min @ ΔP = 10 bar).
• S5: Mid-position function code. S5 usually represents "O-type" mid-position function, where the valve core is in the middle position and all oil ports are closed, used for locking the actuator and maintaining pressure. Other common functions include Y-type (mid-position unloading), H-type (mid-position interconnection), etc.
A5: The selection must be based on accurate system requirements:
The maximum working flow and the highest working pressure required by the system. The rated values of the valve should leave an appropriate margin.
Determine the requirements for linearity, hysteresis, and repeatability based on the application. High-precision closed-loop control requires the selection of models with position feedback (LVDT).
Confirm the type of output signal from the controller (voltage/current) and whether bus control (such as PROFIBUS, CANopen) is required.
Select based on safety requirements and the system's standby state (such as choosing O-type for locking, Y-type for unloading).
Working environment temperature, humidity, vibration conditions, and whether high protection level (such as IP65) is required.
Confirm that the sealing material of the valve (such as NBR, FKM) is compatible with the hydraulic oil used in the system.
A6: The decision to select a model with an integrated amplifier is mainly based on the following considerations:
• Simplification of system wiring: The amplifier is integrated with the valve, reducing external connections and junctions.
Factory pre-adjustment, excellent inter-valve interchangeability: The parameters have been optimally matched, and after replacing the valve, complex debugging is usually not required.
• Facilitates diagnosis and setup: Many integrated amplifiers support parameter adjustment and fault diagnosis via USB or Bluetooth interfaces.
• Saves space: No need to install an additional independent amplifier module in the electrical cabinet.
• Bus control requirements: The AES model directly supports fieldbus communication, facilitating integration into automation networks.
A7: Correct installation is the foundation for ensuring the long-term stable operation of the valve:
1. Oil cleanliness: This is the most important requirement! A high-pressure filter (with a recommended precision of ≤ 10μm) must be installed before the valve to ensure the oil cleanliness reaches NAS 1638 grade 7 or higher. The pipeline must be thoroughly flushed before installation.
2. Installation surface: The surface of the installation base must be flat, clean, and have high flatness (usually ≤ 0.01/100 mm), and the bolts must be evenly tightened in a diagonal sequence.
3. Installation direction: The valve body has an arrow indicating the oil flow direction. The P (inlet), A/B (working oil ports), and T (return oil) must be correctly connected. The coil should typically be installed vertically upwards to prevent debris accumulation and poor heat dissipation.
4. Electrical connection: Use shielded cables to connect the control signals. The shield layer should be grounded at one end, and it should be kept away from the power lines to reduce interference. Ensure that the power supply voltage is stable (such as 24VDC ±10%).
Q8: How to conduct power-on debugging and initial inspection?
1. Low-pressure circulation: Disconnect the control signal of the valve, and allow the oil to circulate at a lower system pressure (such as 30% of the rated pressure) to remove air.
2. Manual testing: For models with a manual emergency button, you can first manually operate the valve core to check if the movement is smooth.
3. Signal testing: Connect the power supply, slowly increase the control signal from 0, and observe if the actuator starts, accelerates, and stops smoothly. Check if the valve's response is proportional to the input signal.
4. Parameter calibration: For models with closed-loop control, calibration of zero position and gain may be required through the accompanying software.
5. Monitoring operation: Check if the valve body temperature is abnormal (it should not exceed 60-70℃), and look for any abnormal noise or leakage.
IV. Maintenance and Troubleshooting
A9: This is one of the most common faults. Possible causes include:
1. Oil contamination: Small particles blocking the valve core is the primary reason. Check and replace the filter element, and test the cleanliness of the oil.
2. Electrical issues: Check if the coil resistance is normal (usually several ohms to several tens of ohms), ensure the wiring is secure, and confirm that the control signal reaches normally.
3. Mechanical jamming: The valve core or valve sleeve gets stuck due to wear, deformation, or installation stress. It needs to be disassembled and cleaned for inspection (this should be done by professionals).
4. Insufficient system pressure: Check if the pump and relief valve are working properly, and ensure there is sufficient pilot pressure or driving force.
Q10: When the valve operates, the flow is unstable and the actuator speed fluctuates. How to troubleshoot?
1. Signal interference: Check if the control signal line is subject to strong electromagnetic interference. Ensure good shielding.
2. Amplifier failure: The parameters of the integrated or external amplifier may drift or components may be damaged. Try replacing or recalibrating the amplifier.
3. Pressure compensator failure: If the valve has a pressure compensation function, the stuck valve core or failure of the spring will cause the pressure difference to be unstable, and the flow will change with the load. Check and clean the compensator.
4. Air in the system: Air mixed into the oil will cause compressibility, resulting in speed and pressure fluctuations. Exhale at the high point of the system.
1. Inspect the sealing components: Aging, wear, or damage during installation are the most common causes. Replace with original or equivalent specifications of sealing components.
2. Check the installation bolts: Are the bolts loose or do they have uneven pre-tightening force? They need to be re-tightened according to the specified torque and sequence.
3. Inspect the valve body or installation surface: Are there any cracks or scratches? Minor scratches can be ground repaired, while severe ones require replacement of the valve body or installation base plate.
A12: Preventive maintenance can significantly extend the lifespan of the valve:
1. Regularly monitor the oil: Follow the prescribed schedule to test the cleanliness, viscosity, and moisture content of the oil, and replace the oil and filters in a timely manner.
2. Regularly inspect electrical connections: Check for any looseness, oxidation, or corrosion of the plugs and sockets.
3. Record operating parameters: Regularly record the response time of the valve, control current, system pressure, etc., to facilitate the early detection of performance degradation trends.
4. Maintain a clean environment: Regularly clean the oil stains and dust on the valve body surface to ensure good heat dissipation.
