JPS6020595B2 - mechanical pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to mechanical pumps, in particular to large oilless high vacuum mechanical pumps.

In many industries, for example in the food processing industry, it is imperative that the air or other gases supplied by mechanical pumps or combustors be free of oil and particles.

To improve the effectiveness of this pump, it is known to include interengaging claw-type rotors in the outer stage and the stages adjacent to the outer stage in multi-stage pumps.

This multi-stage pump has a significant gas transfer volume and re-expansion of the scavenging volume of the previous stage may occur unless prevented from doing so by an inner stage check valve. However, this valve is disadvantageous because it tends to complicate the construction of the pump. An object of the present invention is to provide a mechanical pump which is effective in that it can obtain a high vacuum commensurate with a low power input, and which has a relatively simple structure in that it does not require an inner step check valve. It is.

According to the present invention, a mechanical pump includes a pumping chamber having an inlet and an outlet and adapted to pass the fluid to be pumped, and a pair of shafts extending through the pumping chamber, each shaft having at least two Two interengaging pawl-type rotors are supported in tandem and for rotational movement therewith, each rotor forming one of a complementary pair, each complementary pair occupying a separate position in the pump chamber. , adjacent locations are separated by a partition, and each rotor of a complementary pair at one location is provided on each shaft in an opposite orientation to the rotor of the complementary pair at an adjacent location.

The advantage of a mechanical pump as defined above is that by providing oppositely oriented pairs of rotors in adjacent sections or positions, it is possible to move from one step to the next, with minimal internal step volume, The objective is to enable the direct transfer of gas through the feed holes in the partition wall that separates the stepped portions.

The outlet of one step on one side of the partition in the inner step becomes the inlet of the next step on one side of the partition. The invention will now be described by way of example with reference to the accompanying drawings, in which: FIG.

As shown in FIG. 1, a mechanical pump 1 includes a pump chamber 2 through which a pair of shafts 3 pass.

Each shaft 3 supports three rotors 4, 5, 6 in a rotatable manner. The rotors 4, 5, 6 are constructed in complementary pairs, which are arranged in tandem on their respective shafts 3. The pump chamber 2 is divided by partitions 8, 9 into three spaced positions 10, 11, 12, each of which has a pair of rotors. At its right end (as shown), each shaft 3 carries a timing gear 13, and at its left end (as shown)
One shaft 3 (as shown) can be driven in a known manner by a motor via a fluid coupling (not shown).

Also, with reference to FIGS. 2 and 3, the rotor 4 at Itaka 10
is figure-eight or root-shaped and forms the first or inlet stage portion of the multi-stage pump.

The profile of the rotor 4 minimizes the amount of rotor carryover. This means that the profile of the cooperating rotors 4 means that during rotor interaction the amount of air collected on the discharge side of the rotor returning to the inlet side of the rotor is kept to a practical minimum. This is important because if a pocket of gas is carried over from the exhaust side of the rotor to the inlet side, it will tend to expand, reducing the volumetric effectiveness of the pump. An inlet 15 to the pump chamber 2 is provided, which is located at position 10' as shown.
In communication with this, the partition 9 is provided with an outlet 16 from the position 10 or the inlet stage.

A bypass valve 50 is provided on the inner step, the reason for which will be explained later. Further, referring to FIGS. 4-8, rotors 6 and 6 at positions 11 and 12 are in the form of interengaging pawls.

The rotor 5 in position 11 forms the second or intermediate stage of the multistage pump 1, while the rotor 6 in position 12 forms the third or discharge stage of the pump. The orientation of the rotor 5 is as shown in FIG. 4, with the tip 20 of each rotor pawl facing to the right, while the orientation of the rotor 6 is as shown in FIG. 6, with the tip 21 of each rotor pawl facing left. I can see that you are there.

In other words, the orientation of the rotor 6 is opposite to the orientation of the rotor 5. The partition 8 that divides the intermediate stage and the outer stage forms an arcuate slot 22 that partly forms an outlet from the intermediate stage and partly forms an inlet to the outer stage.

The through arcuate slot 22 is stepped at 23 and forms a channel groove 24 on the right side of the partition (as shown in FIG. 5). Similarly, the slot 22 is stepped at 25 and forms a channel groove 26 on the left side of the partition 8. Channel groove 26 and slot 22 form the inlet to the outlet step. The outlet 30 is formed from the outlet step and is in the form of an arcuate slot in the end wall 31 which together with the partition 8 forms the location 12.

The outlet 30 communicates with the outlet 32 from the pump 1 via a one-way valve 33. In addition, partition 81 and introduction port 4
A conduit 40 is provided leading from 2 to the outlet step.

The inlet 42 is a connection port into which air ballast is introduced. In operation, when the motor drives one shaft 3 due to the timing gear 13, both shafts 3 are driven synchronously, thereby driving the various pairs of rotors synchronously.

The fluid enters the pump chamber 2 at position 10 (inlet stage) through the inlet 15, is compressed by the rotor 4 into the space and from there passes through the boat 16' of the partition 9 to position 1.
1 (intermediate stage). This is indicated by an arrow in the drawing. At position 11, the fluid is compressed by the rotor pair 5 and the fluid is compressed by the slot 22 (position 12 shown in Figures 4, 5 and 6).
(which also serves as an inlet leading to the At position 12, the fluid is compressed by rotor 6 and discharges through outlet 30 and check valve 33.
is discharged through the The single-claw rotor and its cooperation with the inlet, outlet, and silling are shown in FIG. Fluid enters the reduced space at location 12 through the inlet and is discharged through the outlet 30 as the rotor 6 rotates in the direction of the arrow. An important feature of this arrangement of the single-jaw rotor and its cooperating mouth is that the fluid trapped between the two rotors (with the pawls 21 in engagement with each other) has an inlet covered by the rotor 6. Rather than expanding directly into 22, it initially re-expands into the contraction space and only a portion of the inflation gas is exposed when the inlet 22 is removed from the rotor. This operating principle allows higher pressure ratios to be obtained than with conventional designs. The fluid to be conveyed enters the inlet stage through the inlet 15, is pumped there and discharges through the slot 22 to the final outlet stage, where it is discharged via the outlet 30, the check valve 33 and the outlet 32.

When the pump turtle is used in high vacuum applications, the scavenging volume of the rotor 6 is primarily at low pressure, and the gas exiting from the outlet 32 cannot re-enter the scavenging volume unless prevented from doing so by the check valve 33. try to

Connection 42 allows air ballast to enter the exhaust volume of the outlet step when it is insulated from its inlet.
When delivering steam, the air ballast is compressed with steam, thus allowing a mixture of air and steam to be delivered to the atmosphere before the steam liquefies. Additionally, air ballast is used to move hot gases away from the exhaust side of the scavenging volume of the outlet stage. Bypass valve 5 is provided in the first stage section. This is because the first stage section now has a larger capacity than the intermediate stage section and the outlet stage section. Bypass valve 50 operates to avoid establishing excessive inner stage pressure.

The pumps described above do not have check valves in the partitions dividing the various positions or stages of the pump.

By reversing the orientation of the two pairs of engaging pawl-type rotors, this allows gas to be transferred from one stage to the next through the perforations in the inner stage partitions with the smallest internal stage volume. make it possible. In fact, the outlet of one step becomes the inlet of the next step.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the mechanical pump, FIG. 2 is a cross-sectional view of the first or introduction stage of the mechanical pump of FIG. 1, and FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2. 4 is a cross-sectional view of the intermediate stage of the mechanical pump shown in FIG. 1, FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4, and FIG. FIG. 7 is a cross-sectional view taken along the line A-A in FIG. 6, and FIG. 8 is a rotor forming the introduction, intermediate, and discharge stages of the mechanical pump in FIG. 1. FIG. 1: Multistage mechanical pump, 2: Pump chamber, 3: Shaft, 4
: Root type rotor "5, 6: Rotor t8, 9: Partition,
10, 11, turtle 2: pump chamber position, 22: slot. FIG. IFIG. 8 FIG. 2 FIG. 3 FIG・muFIG. 5 FIG. 6 F'G. 7

Claims (1)

[Scope of Claims] 1. A pump chamber having an inlet and an outlet for passing the fluid to be delivered, and a pair of parallel shafts extending through the pump chamber, each shaft having at least two Two rotors of the interengaging pawl type are arranged longitudinally and supported for rotational movement therewith, each rotor forming one of a complementary pair, each complementary pair occupying an individual position in the pump chamber and adjacent to each other. A mechanical pump in which the rotors of a complementary pair at one position are provided in opposite orientations to the rotors of a complementary pair at an adjacent position on each shaft, with the positions being separated by a partition. 2. A mechanical pump according to claim 1, wherein the partition has an arcuate through slot, thereby allowing passage of fluid from one location to the next adjacent location. 3. The mechanical pump according to claim 1 or 2, wherein a one-way valve is located at the outlet from the pump chamber to control passage of fluid through the outlet. 4 Any one of claims 1 to 3
A mechanical pump according to paragraph 1, further comprising means for introducing an air ballast into the pump at a location directly adjacent to the outlet from the pump chamber. 5 Any one of claims 1 to 4
In the mechanical pump according to paragraph 1, another rotor is provided on each shaft in tandem with the at least two rotors, the further rotor being root-shaped and directly adjacent to the inlet to the pump chamber. A pump forming one of a complementary pair occupying a position. 6. The mechanical pump according to claim 5, wherein the bypass valve is provided at the position occupied by the pair of root rotors.