JP2000257581A - Liquid sealing type vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid sealing type vacuum pump capable of being used even at high rotation speed and low rotation speed and being miniaturized. SOLUTION: In a movable vane type vacuum pump using conventional sealing liquid, a clearance A is formed at whole periphery between an outer end face 11 of a vane 10 and an inner wall 15 of a casing 1. A vane chamber 17 having a clearance B at a dead point D is formed between an outer wall 16 of a rotor 3 and the inner wall 15 of the casing 1, and a suction port 18 and a discharge port 18 are provided in either of a front end plate and a rear end plate 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-sealed vacuum pump dedicated to mounting on a vehicle, which can be miniaturized and is applied to a collection suction tank truck or the like capable of providing a large air flow.

[0002]

2. Description of the Related Art Conventionally, a collection suction tank truck for collection and use of a tank mounted on a truck chassis is generally composed of a waste collection tank truck for sucking liquid such as waste liquid and sewage, and a solid tank such as sludge and powder. It is used separately from a sludge collection tank truck that sucks things. This is because the type of vacuum pump used is different. A movable vane type vacuum pump (vane type vacuum pump) is used for a waste liquid collecting tank truck for sucking a liquid, and the vehicle is made compact (more than a two-ton truck) and has mobility. Sealed-type vacuum pumps (elmo-type vacuum pumps) are used for sludge collection tank vehicles that suck solids, and many vehicles are large vehicles (6 ton trucks or more). These two types are mainly used as vacuum pumps mounted on vehicles.
In the case of a waste liquid collection tank truck that sucks a liquid, the inside of the tank is depressurized by a vacuum pump to suck the liquid into the tank via a suction hose. Therefore, since a relatively higher degree of vacuum than the pump air volume is required, a vane type vacuum pump is used. FIG. 1 shows a schematic cross-sectional view of a vane type vacuum pump as an example. An outer guide ring (42) is fitted over the entire surface in the casing (41), and a plurality of vanes (4
3) rotates while sliding. The front and rear end faces in the axial direction of the casing are airtightly closed by an end plate (45) having a rotating shaft (44) penetrating outside, and an inner guide ring (46) is provided inside each end plate. I have. The rotor (47) is mounted eccentrically with respect to the casing, and the rotor is provided with a plurality of vane grooves (48) in the normal direction, into which vanes are mounted. When the rotating shaft rotates, the vane reciprocates in the vane groove while the inner and outer end faces are constrained by the outer guide ring and the inner guide ring, thereby forming an airtight vane chamber (49) between the vanes. The vane-type vacuum pump performs a pumping operation by changing the volume of the vane chamber due to rotation. By increasing the amount of eccentricity, the volume change of the vane chamber can be increased,
The pump itself can be downsized accordingly. Oil is sealed in the pump to maintain airtightness. On the other hand, in the case of a sludge collection tank truck that mainly sucks solid matter such as sludge, the solid matter is sucked into the tank via a suction hose by the air volume of a vacuum pump. Therefore, since an air volume is required rather than a degree of vacuum, an elmo type vacuum pump is generally used. FIG. 2 shows a schematic cross-sectional view of an elmo vacuum pump as an example. When an appropriate amount of sealing water (62) is placed in the casing (61) and the impeller (63) mounted eccentrically with respect to the casing is rotated, the sealing water is centrifugally forced to have a width E along the inner wall of the casing. Circulates and creates a circular void (64) in the center. In this way, two wings (6
The liquid level in the blade chamber (66) during 5), that is, the inner diameter surface of the water recirculation, moves in the circumferential direction as the impeller rotates, and performs a piston action. By this piston action, air can be sucked and exhausted through the suction port (68) and the discharge port (69) on the end plate (67) inscribed in the impeller.
Sealing water plays an important role in that a certain amount of water always flows in from the suction port to create water recirculation in the pump and is discharged together with gas from the discharge port, but also plays a role in removing heat of compression.

[0003]

The collection suction tanker truck is divided into two types, but at the collection site of actual waste liquid or sludge, a large amount of solid matter is mixed in the waste liquid, or the waste liquid is extremely wet. Sludge often contains a lot of water,
In order to use various types of collection suction trucks adapted to the situation at the site, a unique device is required, which often impedes the work efficiency. For example, a waste liquid collection tank truck using a vane type vacuum pump is not suitable for sucking solids. In practice, solids are often mixed in a liquid, but it is not possible to suck only solids with a small air volume of a vane-type vacuum pump. Therefore, in such a case, the following two methods are adopted. One is to use a vacuum tank. That is, this method is a method of sucking air by separating the tip of the suction hose from the liquid surface, instantaneously increasing the air volume in the hose, and sucking solids with the momentum. However, this method increases the pressure in the tank momentarily,
An impact is generated in the tank, resulting in damage to the tank and the pump. In addition, since the pressure inside the vacuum tank to which the air is once sucked is greatly increased, it takes time to reduce the pressure again, thereby deteriorating the working efficiency. Another method is to increase the pump airflow by increasing the rotation of the vane type vacuum pump. In the vane type vacuum pump, the vane is strongly pressed against the outer guide ring due to the centrifugal force generated by the rotation and generates frictional heat. Therefore, lubricating oil having high thermal stability is used as the sealing liquid. The oil temperature rises rapidly when the engine is kept rotating at a high speed in order to increase the discharge air volume of the pump. If the degree of vacuum further increases and the flow of air stops, the sealing oil accumulates in the pump and becomes difficult to move, so that the oil temperature further increases and becomes extremely high. If such a state continues for a long time, the oil film on the guide ring breaks, causing abnormal wear of the vane and the guide ring, resulting in abnormal noise and damage. In addition, this method causes excessive sliding resistance of the vane, increases the rotational torque and power consumption of the pump, and accelerates the deterioration of the oil seal, thereby significantly impairing the economic effect. Therefore, the vane-type vacuum pump is excellent for use in vehicles because it can be downsized and can be used at low speed rotation, but has a drawback of low air volume, which makes it difficult to apply a waste liquid collection tank truck at an actual site. There is a side. On the other hand, it is conceivable to use an elmo vacuum pump having a large air volume. However, the elmo vacuum pump has a disadvantage that the pump has a large outer shape and a high rotational speed, and is not suitable for use in a small vehicle.
Among the waste liquid collection tank vehicles, the 2-ton vehicle class has high mobility and is suitable for narrow roads, and is most active in society. 2
The on-vehicle pump mounted on the tonnage truck is usually located below the chassis frame at the rear of the engine and is rotated by the engine via the transmission PTO (power take-off device). The normal pump rotation is limited to about 600 to 800 rotations per minute according to the idling rotation of the engine. It is necessary to meet such conditions in order to be economically mounted on a small vehicle. Elmo-type vacuum pumps are disadvantageous in that they are large in size, high in rotation speed, and large in driving force. In order to increase the air volume of the elmo-type vacuum pump, the diameter of the impeller must be increased and the difference from the diameter of the casing must be increased. As a result, the outer shape of the pump increases. When the impeller is enlarged, the width E of the water recirculation is also increased, and the driving force of the pump is increased. In addition, since centrifugal force must be applied to the water reflux, the pump must also rotate at a high speed of 1400 rpm or more. Therefore, in view of the size, rotation speed and driving force of the pump,
It is difficult to drive by O. Actually, even when installing an Elmo type vacuum pump on a large vehicle, it is mounted on the undercarriage and directly connected to the mission to take out the power, and there is no pump with a minimum size of 500 mm or less even in the smallest size . That is, it is structurally unsuitable for mounting on a vehicle, and it is not economical because the amount of sealed water is large and the power consumption is large. However, a pump with a large air volume is required to suck solids, and there is no effective pump that can replace the Elmo vacuum pump in the existing pumps. Although the conventional problems have been described above, an object of the present invention is to provide a vacuum pump that can be economically mounted on a small mobile vehicle and that can suck both liquids and solids. Therefore, the problems of the pump to be solved by the present invention are as follows. (B) The external dimensions of the pump can be reduced. That is, it is desirable that the size can be reduced to the same extent as a conventional vane type vacuum pump for use in a small vehicle. (B) Pump exhaust air volume is large. That is, a larger air volume is required than the conventional vane type vacuum pump,
It is not always necessary to increase the air volume, but it is more economical if it can be increased as needed. (C) The pump speed is low. That is, when a large amount of air is required, a high rotation is unavoidable, but a low rotation such as the idling of the engine is usually economically and environmentally desirable. The present invention provides a method for solving the above problems.

[0004]

The present invention will be described with reference to the drawings corresponding to the embodiments. 3 and 4 show an embodiment of the liquid ring type vacuum pump according to the present invention. A rotor (3) having a rotation axis (2) in the axial direction of the cylindrical casing (1) is mounted eccentrically inside the casing (1). The front and rear openings in the axial direction of the casing (1) are closed by a front end plate (5) and a rear end plate (6). A bearing (4) is provided on each of the front end plate (5) and the rear end plate (6) to support the rotation shaft (2), and the rotation shaft (2) is moved outward from the front end plate (5).
Are projected so that they can be rotated from the outside while maintaining airtightness. At the center inside the front end plate (5) and the rear end plate (6), a cylindrical inner guide ring (7) having a fixed width and being concentric with the casing (1) is provided. Further, a cylindrical outer guide ring (8) having a constant width is provided on the inner surface of the opening of the canning (1) in contact with the front end plate (5) and the rear end plate (6). A plurality of vane grooves (9) having a fixed width and depth are provided in the axial direction of the rotor (3) over the entire length in the normal direction from the outer periphery to the center of the rotor (3). A rectangular plate-shaped vane (10) is slidably mounted in the vane groove (9). The outer end surface (11) of the vane (10) is slidably in contact with the inner diameter surfaces of the front and rear outer guide rings (8). The inner end surface (12) of the vane (10) is slidably in contact with the outer diameter surfaces of the front and rear inner guide rings (7). The front end face (13) and the rear end face (14) on the axial side of the vane (10) are slidably in contact with the front end plate (5) and the rear end plate (6), respectively. The vane (10) is configured to reciprocate in the normal direction in the vane groove (9) with the rotation of the rotation shaft (2). A certain amount of sealing liquid is filled in the pump in order to keep the inside of the pump airtight and to cause a pumping action. The pump configured as described above is further configured as follows. (A) Outer end surface (11) of vane (10)
And the inner wall (15) of the casing (1) to form a gap A over the entire circumference. (B) A gap B is formed between the outer wall (16) of the rotor (3) and the inner wall (15) of the casing (1) at the dead center D.
The vane chamber (17) is formed so as to have the following. (C) Inlet (18) and outlet (19) in either front end plate (5) or rear end plate (6)
Is provided.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. A rotor (3) having a rotation axis (2) in the same direction as the axial direction of the cylindrical casing (1) is attached to the inside of the casing (1) while being eccentric by H. A sealing material (22) is disposed at each of the front and rear openings in the casing (1) in the axial direction, and the front end plate (5) and the rear end plate (6) are bolted (2).
Attach in 3) and close hermetically. A bearing (4) is provided on each of the front end plate (5) and the rear end plate (6) to support the rotating shaft (2). The rotating shaft (2) is projected outside the front end plate (5), and a bearing cover (25) provided with a rotating seal material (24) is attached with bolts (26) and packing (27) to maintain airtightness. It is configured to be able to rotate from the outside while doing. A blind bearing cover (28) is attached to the rear end plate (6) by bolts (2).
9) and airtight with packing (30). At the center boss (31) facing the inside of the front end plate (5) and the rear end plate (6), a cylindrical inner guide ring (7) having a constant width and concentric with the casing (1) is provided. . A cylindrical outer guide ring (8) having a constant width is provided on the entire inner surface of the opening of the casing (1) in contact with the front end plate (5) and the rear end plate (6). Six vane grooves (9) having a constant width and depth are provided along the entire length of the rotor (3) in the normal direction from the outer periphery to the center of the rotor (3). A rectangular plate-shaped vane (10) is slidably mounted in the vane groove (9). Outer end surface (11) of vane (10)
Are slidably in contact with the inner diameter surfaces of the front and rear outer guide rings (8). The inner end surface (12) of the vane (10) is slidably in contact with the outer diameter surfaces of the front and rear inner guide rings (7). The front end face (1
3) and the rear end face (14) are slidably in contact with the front end plate (5) and the rear end plate (6), respectively. The vane (10) is configured to reciprocate in the normal direction in the vane groove (9) with the rotation of the rotation shaft (2). A certain amount of sealing liquid is filled in the pump to keep the inside of the pump airtight and to cause a pumping action. The pump structure configured as described above is similar to a generally used vane-type vacuum pump and is a known structure. The present invention is further configured as follows, and these portions are structures which are features of the present invention. (A) A gap A is formed over the entire circumference between the outer end surface (11) of the vane (10) and the inner wall (15) of the casing (1).
To form (B) A gap B at a dead center D between a cylindrical outer wall (16) of the rotor (3) sandwiched between two vanes (10) and an inner wall (15) of the casing (1). The vane chamber (17) is formed so as to have the following. (C) At the bottom of the rear end plate (6),
8) and a discharge port (19) are provided.

The structure of the present invention is as described above. When this structure is used, the following is performed. FIG. 5 shows the flow of the sealing liquid when the pump is rotated at a high speed. When the pump is filled with the sealing liquid and rotated at a high speed, the sealing liquid is applied to the outer end face of the vane (11).
While passing through a small gap A between the casing and the inner wall (15) of the casing, the casing is pressed against the inner wall (15) of the casing under centrifugal force and refluxed in the casing. Eventually, a reflux (sealed liquid reflux) by the sealed liquid having a width substantially equal to the gap B is provided between the inner wall (15) of the casing (1) and the cylindrical outer wall (16) of the rotor (3). And a cylindrical space is created in the central part. Therefore, as the rotor (3) rotates, the volume in the vane chamber (17) expands and contracts due to the eccentricity H, and a variable space is formed between the sealed liquid recirculation and the vane. Action occurs. That is, it functions as an elmo vacuum pump. Since FIG. 5 shows clockwise rotation, the right half shows the expansion stroke (intake stroke) and the left half shows the compression stroke (exhaust stroke). The sealing liquid is always supplied from the suction port (18) on the right side and is discharged together with air from the discharge port (19) on the left side. FIG. 6 shows the flow of the sealing liquid when the pump is rotated at a low speed. When the rotation of the pump is reduced to a low speed and the centrifugal force reduces the sealing liquid reflux to a stage where the sealing liquid is not formed in the casing (1), the sealing liquid in the vane chamber (17) becomes turbulent, and the sealing liquid becomes minute. Attempts to flow through the gap A to the lower pressure vane chamber. However, since the gap A is small enough,
Even though some pressures flow, most of the pressure is maintained in the vane chamber. Can be used as a vacuum pump. That is, the pump can be used as a pump having the characteristics of both an elmo-type vacuum pump and a vane-type vacuum pump depending on the level of the pump rotation.

[0007]

According to the present invention described above, 3
We will discuss the effects of the two issues. (B) Regarding the condition that the outer shape of the pump is small, there is no great difference in structure from the conventional vane type vacuum pump which is most suitable for mounting on a small vehicle, and the pump can be made almost the same shape. The effect is obtained. (B) Regarding the large pump exhaust air volume, the capacity of the vane chamber can be increased because the structure is simpler than that of the conventional vane type vacuum pump. In addition, since the number of rotations of the pump can be increased, a larger air volume can be obtained than with the vane type vacuum pump. Further, since the pump of the present invention uses a movable vane, not only can the eccentric amount H be made larger than that of a conventional elmo-type vacuum pump having a fixed impeller, but also the width B of the sealed liquid recirculation can be increased. Can be smaller. Therefore, since the volume of the variable space in the vane chamber can be increased, the exhaust air volume of the pump can be increased as compared with an Elmo vacuum pump having the same external dimensions. (C) As described above, the condition that the pump rotation is low can be dealt with by selectively using the characteristics of both the Elmo vacuum pump and the vane vacuum pump depending on the level of the pump rotation. In a normal liquid-centered suction operation, the pump is used for low-speed rotation of the engine at about idling. When a large amount of exhaust air is required, such as for suction of solids, the high-speed rotation is very economical. The pump of the present invention can rotate at high speed even if it is a vane type. That is, in the conventional vane-type vacuum pump, the vane rotates in contact with the inner wall of the casing, so that centrifugal force and pressure are applied to the vane, and the vane tip is pressed against the inner wall of the casing and rotates. Resistance occurs and a large rotational force is required. Therefore,
High speed rotation is difficult. On the other hand, in the case of the present invention, the outer end surface (11) of the vane is connected to the inner wall (1) of the casing.
The outer end surface (11) is only in contact with the inner guide surface of the outer guide ring (8) with a certain width. Moreover, the gap A at the tip of the vane is sufficiently small, and the flow velocity of the sealing liquid passing through the gap A is very fast, so that the vane receives a repulsive force in the center direction. Since the repulsive force cancels the centrifugal force, the sliding resistance applied to the inner and outer guide rings by the vane becomes very small, so that high-speed rotation becomes possible. As described above, the present invention can provide a sufficient solution to the "problem to be solved by the invention" presented at the outset, and can achieve a great economic effect. In addition, the following economic effects can be expected. (D) Since the vane is not in contact with the inner wall of the casing, the material strength and heat resistance of the vane itself can be reduced, the weight can be reduced, and the power consumption can be reduced accordingly. (E) Since the vane is not in contact with the inner wall of the casing, frictional heat due to sliding is not generated, so that a rise in the sealing liquid temperature can be suppressed and the consumption of the sealing liquid due to evaporation can be reduced. (F) By making the gap A sufficiently small, the gap B can also be made small, so that the width of the sealed liquid recirculation becomes small, and power consumption can be reduced accordingly. (G) Above all, by operating the pump rotation in accordance with the working conditions, it is possible to use the pump capacity effectively to the minimum necessary, which results in the greatest reduction in power consumption. As described above, the liquid ring vacuum pump according to the present invention is:
While exploring work areas that were difficult to solve in the past,
This brings greater economic effects than before. With the advent of the small collection tank truck equipped with the liquid ring type vacuum pump of the present invention, waste liquid, solid waste and sludge can be suctioned without distinction, and the suction work by the collection tank tank is made universal, and It is intended to dramatically improve work efficiency. In addition, since it will be possible to achieve a great economic effect, it will greatly contribute to solving environmental problems which are most important in the 21st century and to economic development of the environmental industry.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a conventional vane type vacuum pump.

FIG. 2 is a schematic cross-sectional view of a conventional elmo-type vacuum pump.

FIG. 3 is a schematic cross-sectional view of the liquid ring vacuum pump of the present invention (a cross-sectional view taken along the line FF in FIG. 4).

FIG. 4 is a schematic vertical cross-sectional view of the liquid ring vacuum pump of the present invention (a cross-sectional view taken along the line GOPG in FIG. 3).

FIG. 5 is a diagram of a predicted flow of a sealed liquid when the liquid-sealed vacuum pump of the present invention is rotated at a high speed.

FIG. 6 is an illustration of a flow of a sealed liquid when the liquid ring vacuum pump of the present invention is rotated at a low speed.

[Explanation of symbols]

Reference Signs List 1 casing 13 front end face of vane 2 rotating shaft 14 rear end face of vane 3 rotor 15 inner wall of casing 4 bearing 16 outer wall of rotor 5 front end plate 17 vane chamber 6 rear end plate 18 suction port 7 inner guide ring 19 discharge port 8 outer Guide ring 9 Vane groove 10 Vane 11 Vane outer end face 12 Vane inner end face

Claims (1)

[Claims] 1. A rotor (3) having a rotating shaft (2) in the axial direction of a cylindrical casing (1) is eccentrically mounted inside the casing (1), and both ends of the casing (1) in the axial direction are attached. Each is closed by a front end plate (5) and a rear end plate (6) provided with a bearing (4), and the rotation shaft (2) is projected outside the front end plate (5) to maintain airtightness and to close the outside. The inner guide ring (7) concentric with the casing (1) is provided at the center inside the front end plate (5) and the rear end plate (6), respectively. An outer guide ring (8) is provided over the entire periphery of the portion where the rear end plate (6) and the casing (1) are in contact with each other, and the rotor (3)
A plurality of vane grooves (9) having a constant width and depth in the normal direction from the outer periphery of the rotor are provided in the axial direction of the rotor (3), and the rectangular plate-shaped vane (10) is slidably slidable. ). The outer end face (11) of the vane (10) is slidably in contact with the inner diameter of the front and rear outer guide ring (8), and the inner end face (12) of the vane (10) is formed on the front and rear inner guide ring (7). The front end surface (13) and the rear end surface (14) of the vane (10) on the axial direction slidably contact the front end plate (5) and the rear end plate (6), respectively. A pump using a sealed liquid in which the vane (10) reciprocates in the normal direction in the vane groove (9) with the rotation of the rotating shaft (2). A gap A is formed over the entire circumference between the outer end surface (11) of (1) and the inner wall (15) of the casing (1). (B) The outer wall (16) of the rotor (3) and the casing (1) At the dead center D between the inner wall (15)
(C) a suction port (18) and a discharge port (19) in either the front end plate (5) or the rear end plate (6).
A liquid ring vacuum pump characterized in that it is configured to provide: