Valve assembly

A valve assembly includes a sensing device, a main spring, a bonnet located below the sensing device, a piston with a through hole, and a valve stem connected with the sensing device and having a penetrating part through the through hole. The sensing device drives the valve stem to drive the piston. The valve assembly also includes an auxiliary spring arranged between the bonnet and the piston. The penetrating part is longer than the depth of the through hole and the valve stem is slidably coupled in piston. The valve assembly can prevent the valve stem from transferring the force of the main spring to the piston, so as to avoid damaging the valve port, the valve stem, and the piston when the force of the main spring is too large.

TECHNICAL FIELD

The present invention relates to a valve assembly.

BACKGROUND ART

Valve assemblies play a very important role in the automatic control of modernized factories. Factory production depends on the correct distribution and control of flowing medium. Regardless of energy exchange, pressure decrease or simple container charging, the control needs to be completed by final control elements, and especially, valve assemblies are the most commonly used type of the final control elements. Valve assemblies which are used for adjusting pressure parameters adjust the set values of the pressure by changing the compression amounts of the springs via valves to stabilize the pressure of fluid within the needed pressure range. As shown inFIG. 1, the working principle is that a signal pipe101needs to be connected to a pressure tapping point to be sensed and controlled, an actuator102is enabled to sense the pressure of the pressure tapping point, and when the force produced when the pressure of the pressure tapping point acts on the lower part of a diaphragm105is larger than the force of a main spring106, the diaphragm105moves upwards to drive a valve stem107and a piston108to move upwards and the piston108leaves a valve port to realize a pressure regulator opening action. When the pressure of the pressure tapping point is smaller than the force of the main spring, the piston moves downwards to be in contact with the valve port109to realize the goal of closing, wherein the closing force is fully provided by the main spring106.

During the realization of the present invention, the inventor finds that the prior art at least has the following problems: when the force of the main spring is too large, although a lower limiting block110limits the downward stroke of the valve stem107, due to accumulation of various errors, the limiting block110cannot play a very good limiting role. The force of the main spring is still transferred to and concentrated on a valve core assembly (valve stem107, piston108and valve port109). For this reason, the valve core assembly can be damaged, the valve may not to work normally and unnecessary losses are caused.

BRIEF SUMMARY

The present invention provides a valve assembly to solve the above-mentioned technical problem.

In accordance with a first exemplary aspect of the present invention, a valve assembly includes a sensing device, a piston with a center through hole, and a valve stem. An upper end of the valve stem is connected with the sensing device, and a lower end of the valve stem is provided with a penetrating part which penetrates through the center through hole so as to enable the valve stem to be connected with the piston. The sensing device drives the valve stem to drive the piston to move up and down. An auxiliary spring which is always in a compressed state is arranged on the piston. The length of the penetrating part is greater than the depth of the center through hole, and the valve stem is slidably coupled in the center through hole of the piston.

In one preferred form, the valve stem further includes a main body part which is connected with the penetrating part, and an axial clearance exists between the main body part and the piston.

In another preferred form, the connection between the main body part and the penetrating part is a stepped structure.

In another preferred form, the valve stem further includes a main body part which is connected with the penetrating part, and the outer diameter of the main body part is equal to the outer diameter of the penetrating part.

In another preferred form, a main spring is arranged above the sensing device, and the force of the main spring is transferred to the valve stem through the sensing device.

In another preferred form, the valve assembly further includes a limiting block which is used for limiting the stroke of the valve stem to keep the axial clearance.

In another preferred form, the sensing device is a sensing chamber including a sensing element and a shell, wherein the valve stem penetrates through the sensing element and the sensing element drives the valve stem to move up and down.

The valve assembly according to the present invention has the advantages that since the auxiliary spring, which is in a compressed state, is arranged between the bonnet and the piston, the length of the penetrating part is larger than the depth of the center through hole, such that when the force of the main spring is too large, the diaphragm drives the valve stem to move downwards; since the valve stem is slidably coupled in the center through hole of the piston, the penetrating part and the piston move relative to one another and the force of the main spring to the valve stem cannot be transferred to the piston; and in addition, since the auxiliary spring is always in a compressed state, the auxiliary spring always applies a downward acting force to the piston, such that the auxiliary spring not only provides the closing force, but the axial clearance is always kept between the main body part of the valve stem and the piston to protect the valve core assembly from being damaged.

In accordance with a second exemplary aspect of the present invention, a valve stem includes a main body part which is connected with a piston and an axial clearance exists between the main body part and the piston. When the force of the main spring acts on the valve stem, because the axial clearance exists between the main body part and the piston, the force of the main spring cannot provide a closing force for the valve port. Since the auxiliary spring is always in a compressed state and always applies a downward acting force to the piston, the auxiliary spring not only provides the closing force but serves to maintain the axial clearance between the valve stem and the piston. Therefore, the piston is only subjected to the closing force provided by the auxiliary spring, and because the closing force is far smaller than the force of the main spring, this protects the valve core assembly from being damaged.

In accordance with a third exemplary aspect of the present invention a valve stem includes a main body part having an outer diameter equal to an outer diameter of a penetrating part, such that the piston can freely move up and down relative to the valve stem; and in addition, because the outer diameter of the main body part is equal to the outer diameter of the penetrating part, the valve stem has a uniform outer diameter, which can be produced easily and at a lower manufacturing cost.

DETAILED DESCRIPTION OF THE DRAWINGS

The technical solution of the present invention is further described below in combination with the drawings and the embodiments. The description of the preferred embodiments below is just exemplary and is absolutely not limited to the present invention and the application or using method thereof.

Example I

As shown inFIG. 2, a valve assembly2constructed in accordance with the teachings of the present invention includes a spring housing210, a sensing device220which is located below the spring housing210, and a bonnet230, a piston240and a valve port250which are sequentially located below the sensing device220. The valve assembly2further includes a valve stem260which penetrates through the sensing device220, the bonnet230and the piston240, wherein a main spring211and an adjusting screw rod212are arranged in the spring housing210, one end of the adjusting screw rod212is connected with the main spring211, and the other end of the adjusting screw rod212extends outside of the spring housing210. The sensing device220is a sensing chamber consisting of a diaphragm221and a shell222thereof. The bonnet230is connected below the shell222of the sensing device. An auxiliary spring270is arranged between the bonnet230and the piston240below the bonnet230. The auxiliary spring270is always in a compressed state and respectively applies upward acting force and downward acting force to the bonnet230and the piston240. A baffle241is arranged on the piston240and the baffle241is provided with a center through hole242penetrated by the valve stem260. One end of the valve stem260is connected with the baffle241and the other end of the valve stem260is connected with the sensing device220.

FIG. 3is a close-up view of the valve stem260provided by the first example of the present invention. The valve stem260includes a penetrating part261which is located in the center through hole242, a main body part262which is connected above the penetrating part261, and an end part263which is located below the baffle241, wherein the end part263connects the valve stem260with the piston240through a nut. The penetrating part261is the part that penetrates through the center through hole242, of the valve stem260. The length of the penetrating part261is larger than the depth of the center through hole242and the penetrating part261is in clearance fit with the center through hole242, so that the penetrating part261can slide up and down in the center through hole242, i.e., the penetrating part261and the center through hole242can produce relative displacement during movement. The outer diameter of the main body part262is larger than the inner diameter of the center through hole242, so as to prevent the main body part262from penetrating through the center through hole242. Since the length of the penetrating part261is larger than the depth of the center through hole242, an axial clearance exists between the main body part262and the baffle241.

As shown inFIG. 2, by rotating the adjusting screw rod212, the main spring211is compressed or extended accordingly and has certain spring force which acts on the sensing device220. Fluid flows into the valve assembly2from an inlet201, and the sensing device220senses the pressure of the fluid at a pressure tapping point. When the force produced when the fluid acts on the lower part of the diaphragm221is larger than the force of the main spring211, the diaphragm221moves upwards to drive the valve stem260to move upwards, thereby driving the piston240to move upwards far away from the valve port250to realize the opening action of the valve port250.

When the force produced when the fluid acts on the lower part of the diaphragm221is smaller than the force of the main spring211, the diaphragm221moves downwards to drive the valve stem260to move downwards. The piston240moves downwards with the valve stem260. Since the auxiliary spring270is always in a compressed state between the bonnet230and the baffle241, the auxiliary spring270applies a downward acting force to the baffle241and the axial clearance is always kept between the main body part262and the baffle241. When the piston240continuously moves downwards and is in contact with the valve port250, the valve stem260continuously moves downwards. At this moment, since the axial clearance exists between the main body part262and the baffle241, and the penetrating part261is in clearance fit with the center through hole242, the penetrating part261moves relative to the baffle241in the center through hole242, i.e., the valve stem260continuously moves downwards relative to the baffle241. The spring force transferred by the main spring211to the valve stem260cannot be transferred to the piston240. However, the auxiliary spring270applies downward acting force to the piston240, so that the piston240can continuously move downwards until the valve port250is fully closed. In this process, the piston240is only subjected to the acting force of the auxiliary spring270and is not subjected to the spring force transferred by the main spring211to the valve stem260. Relative to the force of the main spring211, the acting force produced by the auxiliary spring270is smaller. Thus, when the force of the main spring211is too large, the valve port250, the valve stem260and the piston240are not damaged by the piston240due to too large of a force.

The valve assembly2further includes a limiting block223which is located in the sensing device220. The limiting block223is fixed on the inner surface of the shell222and is located below the diaphragm221. The diaphragm221drives the valve stem260to move downwards and the limiting block223also moves downwards. When the limiting block223is in contact with the inner surface of the shell222below the limiting block223, the shell222stops the diaphragm221and the valve stem260from continuously moving downwards. The limiting block223prevents the downward stroke from being too large due to too large of a force applied to the valve stem260, which facilitates the relative movement of the valve stem260and the piston240, but guarantees that the relative displacement between the valve stem260and the piston240is within an effective range, so as to avoid damaging the parts.

When the valve assembly2is in a working state, the direction of the acting force transferred by the main spring211to the valve stem260and the direction of the acting force applied by the auxiliary spring270to the piston240are always kept to be consistent and downward. The two springs jointly act on the movement of the valve stem260and the piston240. Compared with the case that the auxiliary spring270is not utilized, the main spring211can use small elastic force to achieve the same effect, so that the working accuracy and stability of the valve assembly2are higher.

Example II

FIG. 4depicts another example of a valve stem of a valve assembly4constructed in accordance with the teachings of the present invention. The valve assembly4includes a valve stem460, which comprises a penetrating part461which is located in the center through hole442, a main body part462which is connected above the penetrating part461, and an end part463which is located below the baffle441, wherein the end part463connects the valve stem460with the piston440through a nut. The penetrating part461is the part, which penetrates through the center through hole442, of the valve stem460. The penetrating part461is in clearance fit with the center through hole442, so that the penetrating part461can slide up and down in the center through hole442, i.e., the penetrating part261and the center through hole242are displaced relative to one another during movement. The outer diameter of the main body part262is equal to the outer diameter of the penetrating part442, i.e., the penetrating part and the main body part are respectively a rod object with uniform thickness. The piston240can freely slide up and down relative to the valve stem260. The range of the relative displacement between the valve stem260and the piston240is larger, and is more easily produced at a lower production cost.

Other structures except the valve stem of the valve assembly4provided by this example are identical with that of the valve assembly2provided by the first example, and thus are not repetitively described here.

The exemplary examples provided by the present invention are intended to enable the present disclosure to be more complete and to comprehensively convey the protection scope thereof to one skilled in the art. Examples of a great number of details such as specific parts, devices and methods are described so as to provide comprehensive understanding to the examples of the present disclosure. It is very obvious for one skilled in the art that the details are unnecessarily provided, the exemplary examples can be implemented in various different forms and they shall not be explained as limitations to the scope of the present disclosure. In some exemplary examples, well-known processes, well-known device structures and well-known techniques are not described in detail.

Although terms such as first, second and third can be used to describe various components, parts or portions, these components, parts or portions shall not be limited by these terms; and these terms are only used for distinguishing a component, part or portion. When numerical value terms such as “first” and “second” are used herein, they do not contain sequences or orders, unless otherwise clearly stated in the context. Therefore, under the situation of not departing from the description of the exemplary examples, the first component, part or portion described below can be explained as the term of a first component, part or portion.

Although various embodiments of the present invention have been described herein in detail, it should be understood that the present invention is not limited to the embodiments which are described and shown herein in detail. Other transformations and modifications can be realized by one skilled in the art under the situation of not departing from the essence and the scope of the present invention. All such transformations and modifications shall fall into the scope of the present invention. In addition, all components described herein can be replaced by other technically equivalent components.