Trochoid pump with air ejection port

Abstract

An air ejection port for ejecting air-mixed oil is structured with a first air ejection port provided on the inner peripheral side from an inscribed circle of an outer rotor and a second air ejection port provided on the outer peripheral side from a circumscribed circle of the inner rotor, the air ejection port can have an enlarged port area as the total of area of the first air ejection port and area of the second air ejection port in a state without being in communication with either of a suction port and a discharge port, and a disadvantage that a pump chamber of a previous stroke and a pump chamber of a subsequent stroke communicate with each other through the air ejection port can be avoided.

Claims

1. A trochoid pump with an air ejection port, comprising: a casing; an outer rotor, rotatably arranged in the casing; and an inner rotor, rotatably arranged inside the outer rotor to perform sucking and pressure-feeding of an oil in cooperation with the outer rotor; wherein the casing including: a suction port through which the oil is sucked in a sucking stroke, an air ejection port through which a part of air-mixed oil is ejected in an air ejecting stroke subsequent to the sucking stroke, and a discharge port through which the oil is discharged in a discharging stroke subsequent to the air ejecting stroke; the air ejection port including: a first air ejection port provided on an inner peripheral side from an inscribed circle of the outer rotor, and a second air ejection port provided on an outer peripheral side from a circumscribed circle of the inner rotor.

2. The trochoid pump with an air ejection port according to claim 1, wherein the second air ejection port is arranged at a position close to the circumscribed circle of the inner rotor on the outer peripheral side from the circumscribed circle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an exploded perspective view illustrating a structural example of a trochoid pump with an air ejection port according to an embodiment.

(2) FIG. 2 is a plane view illustrating the structural example of the trochoid pump with an air ejection port according to the embodiment.

(3) FIGS. 3(a)-3(c) are views illustrating an operational example of the trochoid pump with an air ejection port according to the embodiment.

(4) FIG. 4 is a plane view of another structural example of an air ejection port of the trochoid pump with the air ejection port according to the embodiment.

(5) FIG. 5 is a plane view of another structural example of an air ejection port of the trochoid pump with the air ejection port according to the embodiment.

(6) FIG. 6 is a graph indicating an air ejection effect of the trochoid pump with an air ejection port according to the embodiment.

(7) FIG. 7 is a graph indicating a torque of a rotor rotating shaft of the trochoid pump with an air ejection port according to the embodiment.

(8) FIG. 8 is a block diagram illustrating an oil passage using a trochoid pump.

(9) FIGS. 9(a)-9(e) are views for explaining operation of a conventional trochoid pump.

(10) FIG. 10 is a view for explaining problems of a conventional trochoid pump.

EMBODIMENT OF THE INVENTION

(11) In the following, an embodiment of the present invention will be described with reference to the attached drawings. FIG. 1 is an exploded perspective view illustrating a structural example of a trochoid pump with an air ejection port according to the embodiment. FIG. 2 is a plane view illustrating the structural example of the trochoid pump with an air ejection port according to the present embodiment.

(12) As illustrated in FIG. 1, the trochoid pump with an air ejection port according to the present embodiment includes: a casing 1 having a body 1a and a cover 1b, an outer rotor 2 rotatably arranged in the casing 1, an inner rotor 3 rotatably arranged inside the outer rotor 2 to perform sucking and pressure-feeding of oil in cooperation with the outer rotor 2, and a shaft 4 being a rotating shaft for the outer rotor 2 and the inner rotor 3.

(13) As illustrated in FIG. 2, the inner rotor 3 includes four convex portions 3a to 3d and is supported to be rotatable about an axis line C1 in a direction of arrow A as being directly connected to the shaft 4. The outer rotor 2 includes five concave portions 2a to 2e to be engaged with the convex portions 3a to 3d of the inner rotor 3 and is slidably fitted to and supported by a cylindrical face of the body 1a to be rotatable about an axis line C2 in the direction of arrow A. That is, the trochoid pump with an air ejection port of the present embodiment is a trochoid pump having four blades and five nodes.

(14) The cover 1b of the casing 1 is provided with a suction port 21 through which oil is sucked in a sucking stroke, an air ejection port 22 through which a part of air-mixed oil is ejected in an air ejecting stroke subsequent to the sucking stroke, and a discharge port 23 through which oil is discharged in a discharging stroke subsequent to the air ejecting stroke.

(15) Here, the air ejection port 22 includes a first air ejection port 22.sub.-1 arranged on an inner peripheral side from an inscribed circle 31 of the outer rotor 2, and a second air ejection port 22.sub.-2 provided on an outer peripheral side from a circumscribed circle 32 of the inner rotor 3. It is preferable that the second air ejection port 22.sub.-2 is arranged at a position being on the outer peripheral side from the circumscribed circle 32 of the inner rotor 3 and being as close as possible to the circumscribed circle 32 (e.g., at a position contacting to the circumscribed circle 32). According to the above, the air ejection port 22 can be arranged in a state that the air ejection port 22 does not communicate with either of the suction port 21 and the discharge port 23 while preventing communication between a pump chamber of a previous stroke and a pump chamber of a subsequent stroke.

(16) FIGS. 3(a)-3(c) are views illustrating an operational example of the trochoid pump with an air ejection port according to the present embodiment. FIG. 3(a) illustrates a state that the sucking stroke completes, FIG. 3(b) illustrates a state of the air ejecting stroke, and FIG. 3(c) illustrates a state that the air ejecting stroke completes. In FIGS. 3(a)-3(c), the respective states are illustrated for a single pump chamber and regions filled with oil are illustrated with slashes.

(17) First, in the sucking stroke, owing to that the outer rotor 2 and the inner rotor 3 are rotated in the direction of arrow A (counterclockwise), oil is sucked through the suction port 21. FIG. 3(a) illustrates a state the sucking stroke completes (i.e., a state just before the air ejecting stroke starts).

(18) In the state illustrated in FIG. 3(a), the pump chamber does not communicate with either of the suction port 21 and the air ejection port 22 and the volume thereof is the maximum. For increasing the maximum volume of the pump chamber to the extent possible, it is preferable that the air ejection port 22 is formed to have a shape and to be at a position so that a face of the pump chamber on the side of the air ejection port 22 come close to the air ejection port 22 at the time when the sucking stroke completes.

(19) Next, as illustrated in FIG. 3(b), when the outer rotor 2 and the inner rotor 3 are further rotated counterclockwise from a state in which oil is sucked at a maximum, the air ejecting stroke starts and the pump chamber communicates with the air ejection port 22. Accordingly, a part of air-mixed oil is ejected through the air ejection port 22.

(20) When the outer rotor 2 and the inner rotor 3 are further rotated counterclockwise, the air ejection port 22 is closed and the discharging stroke starts. In the discharging stroke, remaining oil is discharged through the discharge port 23. FIG. 3(c) illustrates the state that the air ejecting stroke completes, that is, the state just before the discharging stroke starts. In the state illustrated in FIG. 3(c), the pump chamber does not communicate with either of the air ejection port 22 and the discharge port 23 and the volume of the pump chamber is smaller than the maximum volume illustrated in FIG. 3(a).

(21) The ejection rate (%) of air-contained oil is calculated as “(CP1−CP2)/CP1×100”. Here, CP1 represents the volume of the pump chamber before the air ejecting stroke starts as illustrated in FIG. 3(a) and CP2 represents the volume of the pump chamber after the air ejecting stroke completes as illustrated in FIG. 3(c). FIGS. 3(a)-3(c) illustrate a case that the ejection rate of air-contained oil is 20%.

(22) It is possible to adjust the ejection rate of air-contained oil by changing a size, a position, and a shape of the air ejection port 22 (the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2). FIG. 4 illustrates a structural example of the air ejection port 22 in a case that the ejection rate of air-contained oil is set to 15%. FIG. 5 illustrates a structural example of the air ejection port 22 in a case that the ejection rate of air-contained oil is set to 25%.

(23) FIG. 6 is a graph indicating an air ejection effect of the trochoid pump with an air ejection port according to the present embodiment. The air ejection effect denotes a ratio between an air-containing rate of oil before the air ejecting stroke and an air-containing rate of oil discharged through the discharge port 23 after the air ejecting stroke. The air ejection effect can be calculated as follows.
“(1−(an air containing rate of discharged oil from a trochoid pump with an air ejection port)/(an air containing rate of discharged oil from a trochoid pump without an air ejection port))×100”

(24) FIG. 6 indicates the air ejection effect when the ejection rate of air-contained oil is set to 20% with a φ54 rotor. Symbols “⋄”, “□”, “Δ” indicate air ejection effects in the conventional art each provided with only a single air ejection port having different port area (φ2 equivalence, equivalence, φ3.9 equivalence). In contrast, symbol “◯” indicates an air ejection effect in a case that the first air ejection port 22.sub.-1, (φ3.9 equivalence) and the second air ejection port 22.sub.-2 (φ5.5 equivalence) are arranged as the present embodiment.

(25) As illustrated in FIG. 6, even in the conventional art, the air ejection effect can be enhanced to some extent by enlarging port area of the air ejection port. However, there is a limit on enlarging port area of a single air ejection port in a state that the air ejection port does not communicate with either of a suction port and a discharge port while preventing communication between a pump chamber of a previous stroke and a pump chamber of a subsequent stroke. That is, there is a limit on enhancing the air ejection effect. Symbol “Δ” indicates a vicinity of the limit.

(26) In contrast, when the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2 are arranged as the present embodiment, port area of the air ejection port 22 (the total area of the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2) can be enlarged, as indicated by symbol “◯”, in a state that the air ejection port 22 does not communicate with either of the suction port 21 and the discharge port 23 while preventing communication between a pump chamber of a previous stroke and a pump chamber of a subsequent stroke. Accordingly, the air ejection effect can be enhanced compared to the conventional case.

(27) The test result of FIG. 6 indicates that an air ejection effect can be obtained even when the air ejection port 22 is provided on the outer peripheral side from the circumscribed circle 32 of the inner rotor 3. At a region where the suction port 21 and the air ejection port 22 are not concurrently opened as well as the discharge port 23 and the air ejection port 22 are not concurrently opened, the air ejection port 22 is divided and arranged at a position being on the inner peripheral side from the inscribed circle 31 of the outer rotor 2 and a position being on the outer peripheral side from the circumscribed circle 32 of the inner rotor 3. According to the above, the air ejection effect can be enhanced without deteriorating pumping performance.

(28) FIG. 7 is a graph indicating a torque of the rotor rotating shaft of the trochoid pump with an air ejection port according to the present embodiment. FIG. 7 indicates the torque when the ejection rate of air-contained oil is set to 20% with a φ54 rotor as well. Symbols “⋄”, “□”, “Δ” indicate torques in the conventional art each provided with only a single air ejection port. In contrast, symbol “◯” indicates a torque in a case that the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2 are arranged as the present embodiment.

(29) As illustrated in FIG. 7, even in the conventional art, the torque can be reduced to some extent by enlarging port area of the air ejection port. However, as described above, there is a limit on enlarging port area of a single air ejection port in a state that the air ejection port does not communicate with either of a suction port and a discharge port while preventing communication between a pump chamber of a previous stroke and a pump chamber of a subsequent stroke. Accordingly, there is a limit on reducing the torque. Symbol “Δ” indicates a vicinity of the limit.

(30) In contrast, when the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2 are arranged at the present embodiment, port area of the air ejection port 22 (the total area of the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2) can be enlarged, as indicated by symbol “◯”, in a state that the air ejection port 22 does not communicate with either of the suction port 21 and the discharge port 23 while preventing communication between a pump chamber of a previous stroke and a pump chamber of a subsequent stroke. Accordingly, the torque can be reduced compared to the conventional case. The above result also indicates that air ejection is effectively performed by arranging the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2.

(31) As described above in detail, in the present embodiment, the air ejection port 22 is formed by the first air ejection port 22.sub.-1 provided on the inner peripheral side from the inscribed circle 31 of the outer rotor 2 and the second air ejection port 22.sub.-2 provided on the outer peripheral side from the circumscribed circle 32 of the inner rotor 3. According to the above, it is possible to arrange the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2 in a state without being in communication with either of the suction port 21 and the discharge port 23 and to enlarge port area of the air ejection port 22 as the total area of the first air ejection port 22.sub.-1 and the second air ejection port 22.sub.-2.

(32) Further, in the present embodiment, large port area is ensured by the two air ejection ports 22.sub.-1, 22.sub.-2 separately arranged at different positions instead of enlarging area of a single air ejection port as in the conventional art. Accordingly, it is possible to avoid a problem that a pump chamber of a previous stroke and a pump chamber of a subsequent stroke communicate with each other through the air ejection port 22.

(33) Thus, according to the trochoid pump with an air ejection port of the present embodiment, the air ejection port 22 can have enlarged port area without communicating with either of the suction port 21 and the discharge port 23 and without causing a pump chamber of a previous stroke and a pump chamber of a subsequent stroke to communicate with each other. Accordingly, it is possible to enhance the air ejection effect and reduce the torque of the rotor rotating shaft.

(34) The abovementioned embodiment simply describes an example of an embodiment for actualizing the present invention and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be actualized variously without departing from the substance or main features thereof.