JPH072504Y2 - Closed rotary valve - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention is attached to a silo, a hopper, etc. into which fine powder such as fine powder hydrous silicic acid and ultra fine powder are charged. The present invention relates to a sealed rotary valve that exhibits an air lock function required when pneumatically transporting powder.

(Prior Art) Conventionally, various devices have been used for the purpose of air lock in a powder conveying system for quantitatively or automatically supplying or discharging powder. This is because if there is no airlock function during powder transportation, air leakage will occur at both positive and negative pressures, and the leaked air will affect the related equipment or product quality, leading to stable operation. This is because the adverse effect of In other words, in these powder handling equipment, it is unavoidable that fine powder is entrained with air during supply and discharge, so it is generally a major problem in air conveying systems to keep this entrained air as low as possible. It is said that.

Due to these considerations, in many cases powder-conveying systems that handle powder quantitatively or automatically, such as rotary valves and double dampers, are often used as devices having an airlock function.

As a general rotary valve having an air lock function, there are a normal blade type (a type without a side plate of the rotor) and a shroud blade type with an action of preventing air leakage from the side surface of the rotor. In the device as well, it goes without saying that the amount of the gap between the casing, which is the fixed portion, and the rotor, which is the rotating portion, affects the amount of entrained air.

(Problems to be solved by the invention) By the way, when the powder to be handled becomes finer and finer in recent years, and a rotary valve is used for powder transportation, crushing, classification, storage, etc. The influence of the airtightness on the stability of operation, product quality maintenance, etc. is becoming greater. Therefore, the need to improve the air lock of the rotary valve attached to these devices is also increasing.

In order to improve the function of such an air lock, it is first considered to reduce the amount of entrained air by minimizing the gap between the casing that is the fixed portion and the rotor that is the rotating portion. However, there is a limit to what can be done by this measure due to problems such as machine accuracy and difficulty in strict control over time.

If the gap is designed to be as small as possible, or if an elastic body such as rubber is installed to fill this gap, it is difficult to avoid contact at these parts. As a result, abrasion of the fixed part or rotating part occurs, which causes a problem in the durability of the device.Furthermore, if this wear powder is mixed in the powder of the product being handled, in some cases fatal product There is also the problem of causing quality deterioration.

Therefore, it is required to devise a new device in place of strictly controlling the dimensional relationship between such casings and rotors within an extremely small range.

The present invention has been made from such a viewpoint, and its purpose is to improve the mechanical dimensional accuracy of component parts, to reduce the need for strict control, miniaturization of gaps, and to have excellent durability. The purpose is to provide a closed rotary valve.

Another object of the present invention is to provide a sealed rotary valve capable of exhibiting excellent air lock performance in the air conveyance of fine powder and ultrafine powder.

(Means for Solving the Problems) Therefore, the characteristic of the sealed rotary valve according to the present invention made to realize such an object is that between the pair of disc-shaped shroud blades located at both ends of the rotary shaft. A rotor, which is constructed by arranging a plurality of rotor blades that are spaced apart in the circumferential direction of the rotating shaft, inside a tubular casing, with a minute gap kept on the inner surface of the barrel to rotate the casing. In a sealed rotary valve that conveys powder from the powder supply port on the upper side of the body to the powder discharge port on the lower side, a negative pressure is applied to the rotor blade and shroud blade by suction through the inside of the rotating shaft. In addition to providing an air chamber within the plate thickness that is brought into a state, a shallow recess that is partitioned from the air chamber by the bottom plate partition wall and opens radially outward is provided at the radially outer end positions of these blades, and The partition walls are It is composed of a sintered metal element that is a porous body having a pore size that cannot be exceeded.

In the above-mentioned configuration, the porous plate as the partition wall that divides the concave portion at the tip of each blade and the internal air chamber can be selected and used according to the characteristics of the powder to be handled, but especially sintering A porous metal plate commercially available as a metal element can be preferably used. Specific examples of such a material include, for example, an overuse sintered metal element corresponding to stainless steel SUS316L (porosity 37 to 43%, nominal overprecision 1 to 120 μm, preferably 20 to 40 μm: Sintered Metal Industry Co., Ltd.). Manufactured by the company) can be used.

The gap between the outer periphery of the rotor blade and shroud blade of the present invention and the inner surface of the casing can be selected by design according to the characteristics of the powder to be handled, but generally 0.5 mm
Below, it can be preferably set in the range of about 0.2 to 0.3 mm.

As a powder conveying system to which the rotary valve of the present invention is applied, for example, a system handling an average particle diameter of several μm to several tens of μm is generally exemplified. Not only what can be targeted, average particle size 1
Even for fine powder of less than μm, the effect is exhibited by using the rotary valve of the present invention which uses the excessive sintered metal element corresponding to stainless steel SUS316L. This is because even such small particles are prevented from passing through the eyes of the sintered metal element due to agglomeration into secondary particles, which is effective. To exemplify the types of powders, chemical products such as fine powder hydrous silicic acid, and powders having a relatively low bulk density such as grains, cement, and ceramics are mainly exemplified.

In a particularly preferred embodiment of the present invention, in order to minimize the pressure loss of the intake air from the air chamber provided in the blade, it is possible to prevent the passage of the powder according to the characteristics such as the particle size and the cohesiveness of the powder. It is preferable to use a perforated plate having a pore size as large as possible within the range, whereby a vacuum pump having a small capacity can be selected as the vacuum pump used for the intake.

(Operation) With the above-described configuration, the present invention does not extremely reduce the mechanical gap amount between the tips of the rotor blades and shroud blades, which are rotating bodies, and the inner surface of the casing, which is a fixed body. Even if it is about 0.5 mm or more, powder is filled in the shallow recesses formed at the tips of these blades by suction through a porous plate, and this filled powder fills the gap between the rotating body and the fixed body. Thus, the seal leak from the powder supply side to the discharge side of the rotary valve is prevented, and a good air lock action can be realized.

(Embodiment) The present invention will be described below based on an embodiment shown in the drawings.

FIGS. 1 (a) and 1 (b) are vertical sectional views showing an example of the configuration outline of a sealed rotary valve according to the present invention, in which 1 is a horizontally long cylindrical casing having a body portion An upper side is partially opened to form a powder supply port 2 connected to the hopper. A powder discharge port 3 is formed on the lower side of the casing body so as to face the powder supply port 2.

In this casing, both ends of a tubular body are closed by end walls 1a and 1b, and these end walls 1a and 1b also serve as a structure for supporting a bearing of a rotating body described below.

Reference numeral 4 denotes a rotating body, and this rotating body of the present example constitutes a shroud type rotary valve, and has a rotating shaft 5 and a disc-shaped member which is axially mounted so as to integrally rotate at both end positions in a casing of the rotating shaft. The shroud blades 6,6 are composed of a plurality of rotor blades 7,7,7 ... which are spaced apart from each other in the circumferential direction of the rotary shaft 5 and are installed over the pair of shroud blades 6,6. The blades of (1) and (2) rotate so as to closely face the inner surface of the cylinder of the casing 1. That is, the shroud blade 6 has its disk-shaped outer peripheral surface closely opposed to the inner surface of the cylinder of the casing 1 with a gap of about 0.5 mm in this example, and the rotor blade 7 also has the above-mentioned powder supply and discharge ports. 0.5mm on the inner surface of the barrel of the casing 1 except for
It is designed to rotate in close proximity to each other while maintaining a certain gap.

Reference numeral 8 denotes a driving force transmitting pulley that links the rotating shaft 5 to a driving motor (not shown), and 9 and 10 denote bearings, respectively.

The features of the rotary valve of this example having the above configuration are as follows.
The rotor blade 7 and the shroud blade 6 each have a structure in which two plate bodies are laminated and integrated at a predetermined space, and the space portions between these plate bodies are defined as air chambers 6a and 7a. The intake passage 5 formed in the rotary shaft 5.
The air chambers 6a and 7a are connected to an external negative pressure source through a, and the shallow recesses 6b and 7b that are formed at the tip of the blade radial direction and open to the outside are made of a perforated plate. It is divided by a partition wall (bottom plate of the recess) 11.

These relationships will be described with reference to FIG. 2 and FIG. 3 in which the corresponding portions are shown in an enlarged manner. The rotor blade 7 and the shroud blade 6 have the air chambers 6a and 7a between them by stacking two plates. In this example, in order to form shallow recesses 6b, 7b between the laminated plate bodies in the vicinity of the tips of the rotor blade 7 and the shroud blade 6, in this example, a porous plate made of, for example, stainless sintered metal is used. The plate partition 11 is fixed.

With such a configuration, when the air chambers 6a and 7a are sucked from the external negative pressure source through the intake passage 5a of the rotary shaft, the air flows from the outside to the air chamber side in the partition wall portion as shown in FIG. Occurs, and if powder is present in the surroundings, this powder enters the recess. Then, since the powder will rise to some extent on this recess, it will serve as an air seal by filling the gap between the inner surface of the casing and the blade when the blade rotates.

(Effect of the device) According to the sealed rotary valve of the present invention, the powder is suction-filled into the recess formed at the tip of the rotating blade, and the powder is slightly raised from the blade tip. The effect is obtained that the space between the tips of the blades of the rotating part and the inner surface of the casing that is the fixed part is filled with this powder, and this can be operated while maintaining a good airlock state.

In addition, when the design is such that this gap is made as small as possible, or when an elastic body such as rubber is assembled, wear of the fixed part or rotating part occurs due to inevitable contact, and In addition to the durability problem, wear powder mixed into the powder of the product being handled may cause a fatal deterioration of product quality in some cases. Since the powder to be filled is the powder itself, there is also an excellent advantage that there is no wear of the mechanical part and there is no risk of foreign matter being mixed into the product.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) show an example of the outline of the structure of a sealed rotary valve according to the present invention.
The figure is a vertical sectional front view, and the figure (b) is a vertical sectional side view. FIG. 2 is an enlarged view of the side surface of the rotor blade. Third
The figure is an enlarged view of the radial tip portion of the blade. 1 ... Casing 2 ... Powder supply port 3 ... Powder discharge port 4 ... Rotating body 5 ... Rotating shaft 5a ... Intake passage 6 ... Shroud blade, 6a ... Air chamber 6b ... Recess 7 ... Rotor blade, 7a ... Air chamber 7b ... Recess 8 ... Driving force transmission pulley 9,10 ... Bearing, 11 ... Partition

Claims (1)

[Scope of utility model registration request] 1. A cylindrical body having a cylindrical shape, in which a plurality of rotor blades, which are spaced apart in the circumferential direction of the rotating shaft, are installed between a pair of shroud blades on a disk located at both ends of the rotating shaft. A hermetically sealed rotary that conveys powder from a powder supply port provided on the upper side of the barrel of the casing to a powder discharge port provided on the lower side of the casing by rotating the inside of the casing with a minute gap. In the valve, the rotor blades and the shroud blades are provided with air chambers within a plate thickness that are brought into a negative pressure state by intake air that has passed through the inside of the rotary shaft, and the air chambers are provided at the radially outer end positions of these blades. Is defined by a bottom plate partition wall and has a shallow recess open outwardly, and the partition wall of this bottom plate is composed of a sintered metal element that is a porous plate having a pore size that does not allow the handling powder to pass through. Closed type characterized by Tally valve.