ATOS proportional relief valve QVKZOR-TE-10/65/F 20 in stock

Brand

ATOS/Italian Atos

ATOS proportional relief valves control flow in two ways:

One is on/off control: either fully open or fully closed, the flow is either at its maximum or minimum, with no intermediate state, such as ordinary solenoid direct-flow valves, solenoid directional valves, and electro-hydraulic directional valves.

The other is continuous control: the valve port can open to any degree as needed, thereby controlling the flow rate. These valves can be manually controlled, such as throttle valves, or electrically controlled, such as proportional valves and servo valves.

Therefore, the purpose of using proportional valves or servo valves is to achieve throttling control of flow rate electronically (of course, pressure control can also be achieved through structural modifications). Since it is throttling control, there is inevitably energy loss. Servo valves differ from other valves in that their energy loss is greater because they require a certain flow rate to maintain the operation of the pre-stage control circuit.

ATOS Proportional Relief Valve Product Advantages and Disadvantages

The main valve of a servo valve is generally a spool valve, similar to a directional valve. However, the valve core's switching is not driven by an electromagnet, but by the hydraulic pressure output from the pilot valve. This is similar to an electro-hydraulic directional valve, except that the pilot valve of an electro-hydraulic directional valve is an electromagnetic valve, while the pilot valve of a servo valve is a nozzle-flange valve or jet valve with better dynamic characteristics.

In other words, the main valve of a servo valve is controlled by the output pressure of the pilot valve, and the pressure of the pilot valve comes from the inlet p of the servo valve. If the pressure at p is insufficient, the pilot valve cannot output enough pressure to actuate the main valve core.

We know that when the load is zero, if the four-way spool valve is open, the pressure at p = the pressure at t + the pressure loss at the valve port (ignoring other pressure losses in the oil circuit). If the pressure loss at the valve port is very small, and the pressure at t is zero, then the pressure at p is insufficient to supply the pilot valve to actuate the main valve core, and the entire servo valve fails. Therefore, servo valves have relatively small orifices, requiring a certain pressure loss even when fully open to maintain the normal operation of the pre-stage valve.

Servo valves actually have many disadvantages: high energy consumption, prone to failure, poor contamination resistance, high price, etc. Their only advantage is their highest dynamic performance among all hydraulic valves. This single advantage makes them indispensable in many applications with high dynamic performance requirements, such as aircraft and rocket steering, and turbine speed control. For applications with lower dynamic requirements, proportional valves are generally preferred.

Generally speaking, servo systems seem to be closed-loop control, while proportional systems are mostly used for open-loop control. Secondly, proportional valves offer more variety, including proportional pressure and flow control valves, providing more flexible control than servo valves. Internally, servo valves are mostly zero-overlap, while proportional valves have a certain dead zone, resulting in lower control accuracy and slower response. However, looking at development trends, especially in proportional directional flow control valves and servo valves, the performance difference between the two is gradually narrowing. Furthermore, proportional valves are significantly cheaper than servo valves and have stronger contamination resistance!

The difference between servo valves and proportional valves: There is no strict definition of the difference between servo valves and proportional valves. Because the performance of proportional valves has improved, they are gradually approaching that of servo valves, leading to the emergence of proportional servo valves in recent years.

The difference between ATOS proportional relief valves and servo valves:

The main differences are as follows:

1. Different drive devices. The drive device for proportional valves is a proportional electromagnet; the drive device for servo valves is a force motor or torque motor;

2. Different performance parameters. 2.1 Servo valves have no dead zone in the neutral position, while proportional valves do. Therefore, their applications differ. Servo valves and servo proportional valves are mainly used in closed-loop control systems, while other proportional valve structures are mainly used in open-loop control systems and closed-loop speed control systems.

2.2 Servo valves have a higher frequency response (response frequency), reaching up to around 200Hz, while proportional valves generally have a maximum frequency of tens of Hz.

2.3 Servo valves have higher requirements for hydraulic fluid, requiring fine filtration to prevent clogging, while proportional valves have lower requirements.

3. Valve core structure and machining precision differ. Proportional valves use a valve core + valve body structure, with the valve body also serving as the valve sleeve. Servo valves and servo proportional valves use a valve core + valve sleeve structure.

4. Neutral position functions differ. Proportional directional valves have neutral position functions similar to ordinary directional valves, while servo valves only have an O-type neutral position function (E-type for Rexroth products).

5. Rated pressure drop differs.

The performance of a proportional servo valve falls between that of a servo valve and a proportional valve.

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QVZO-A-20/3-S4 30 The company mainly deals with European and American brands and can source brands from any European country. For example, our key German brands include: BURKERT, DEMAG, HAWE, REXROTH, HYDAC, PILZ relays, FESTO, IFM sensors, E+H, HEIDENHAIN, P+F sensors, SICK, TURCK, and HIRSCHMANN industrial switches. German brands: Hengstler, Murr, Schmersal, Samson, EPRO (Emerson Group)

American brands: MOOG, ASCO, MAC, NUMATICS, PARKER, VICKERS

British brands: Helon Norgren

Italian brands: OMAL, ATOS, CAMOZZI, UNIVER, Camozzi