JPH0746783Y2 - Roots type pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a roots type pump in which a gear for synchronously rotating a pair of rotors is fixed to a rotor shaft via a bush.

[Problems to be Solved by Prior Art and Invention] As is well known, in this type of roots pump, a pair of rotors co-rotates, and each rotor and the inner wall of a rotor housing in which the rotor is housed. The fluid is confined in the formed operation chamber to be alternately pressure-fed to the discharge port, and is often used as a supercharger in an internal combustion engine.

By the way, in the one that adopts the above-mentioned roots type pump as one that rotates at high speed such as a supercharger, the clearance between each component is made strict for high performance, improvement of power loss, reduction of vibration, It is necessary to reduce noise, and when rotating at high speed, the pair of rotors do not interfere with each other, and
To maintain a narrow clearance, high processing accuracy,
Assembly accuracy is required.

For example, in a conventional roots-type pump as disclosed in Japanese Utility Model Laid-Open No. 59-110395, a gear or a pin that rotates a pair of rotor shafts that rotatably support a rotor in synchronization with each other is provided on each rotor shaft. Many are engaged through. However, when the gears are engaged by keying or pinning, meshing noise due to rattle between gears caused by a slight accuracy error in a working process or an assembling process and interference between rotors are likely to occur.

Prevents interference between a pair of rotors by keying, and
In order to maintain a narrow clearance, the position of the keyway,
It is necessary to strictly regulate the dimensions, which not only deteriorates workability, but also increases the number of steps for phase matching between rotors, resulting in a problem that assembly workability is significantly reduced.

On the other hand, compared to keying, pinning allows you to set the gear meshing best suited to the product because it can be assembled by assembling the pinhole after assembling the gear to the rotor shaft. Since it is processed together, it is not mass-produced and has a drawback of poor productivity.

[Purpose of Invention] The present invention has been made in view of the above circumstances.
(EN) Provided is a roots-type pump that is easy to assemble, has excellent mass productivity, can obtain high assembly accuracy, and can reduce noise, vibration, and power loss. It is an object.

[Means and Actions for Solving the Problem] The present invention relates to a roots-type pump in which rotor shafts that respectively support a pair of rotors installed in a rotor housing are connected to each other via gears. And a bush having a wedge-shaped cross section is press-fitted between the gear and the gear inserted into the rotor shaft.

That is, when a bush having a wedge-shaped cross section is inserted between the gear and the rotor shaft, the bush is press-fitted between the rotor shaft and the gear, and the gear is fixed to the rotor shaft via the bush.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 6 show a first embodiment of the present invention, FIG. 1 is an enlarged view of part I of FIG. 5, FIG. 2 (a) is a sectional view of a main part of a gear, and FIG. 2 (b). ) Is a sectional view taken along the line II-II of FIG. 3, FIG. 3 is a front view of the bush, FIG. 4 is a side view of the bush, FIG. 5 is a sectional view of the roots type pump, and FIG. 6 is VI of FIG. It is a VI sectional view.

(Structure) Reference numeral 1 in the figure is a rotor housing, one end of a housing body 1a of the rotor housing 1 is opened, and a housing cover 1b is fixed in contact with the opening. Further, the gear cover 2 is fixed in contact with the housing cover 1b, and the gear chamber 2a is formed therein.

In addition, a pair of rotors 3 and 4 that rotate in synchronization with each other are housed in the housing body 1a. This each rotor 3,
Are rotatably supported by the rotor shafts 5 and 6, and the journals on both sides of the rotor shafts 5 and 6 have the above-mentioned housing main body 1
a, It is supported on the housing cover 1b through a bearing 7. Reference numeral 8 is an oil seal.

Further, a pulley 9 is mounted on the end of the rotor shaft 5 protruding from the housing body 1a. In addition,
The pulley 9 is connected to an output shaft of an engine (not shown) via a belt.

Further, gears 10 and 11 meshing with each other are attached to the bush 1 at the ends of the rotor shafts 5 and 6 which are projected into the gear chamber 2a.
The end faces of the bosses 10a, 11a of the respective gears 10, 11 are abutted on the bearing 7 via the bearings 2.

Furthermore, the end surface of the bush 12 is the rotor shaft.
A nut 13 screwed into the shaft ends of the shafts 5 and 6 presses it via a washer 14.

As shown in FIGS. 2 to 4, the bush 12 is formed into a wedge-shaped cross section having an inclined surface 12a whose outer circumference converges to one side, and a slit 12b extending in the axial direction on one side of the outer circumference. Has been formed.

On the other hand, the gears 10, 11 that are fitted to the outer periphery of the bush 12
The inner surfaces of the bosses 10a, 11a have the same inclination angle θ as the inclined surface 12a of the bush 12.

Also, the maximum diameter DMAX of the outer circumference of the bush 12a is the gear 1
It is formed to be larger than the maximum diameter EMAX of the inner surface of the bosses 10a, 11a of 0, 11 and the minimum diameter DM of the outer circumference of the bush 12.
IN is formed larger than the minimum diameter EMIN of the outer surface of the bosses 10a, 11a of the gears 10, 11 (DMAX> EMAX, DMIN> EMI
N).

Further, the difference between the minimum outer diameter DMIN and the inner diameter D of the bush 12 is slightly smaller than the difference between the minimum inner diameter EMIN of the gears 10 and 11 and the diameter d of the shaft end portions of the rotor shafts 5 and 6. Largely formed (DMIN-D> EMIN-d).

The rotor housing 1 is interposed in the intake pipe of the engine, and the air sucked from the intake port is forcibly supercharged into the combustion chamber through the exhaust port.

(Operation) Next, a procedure for assembling the roots type pump having the above configuration will be described.

First, the rotor shafts 5 and 6 on which the rotors 3 and 4 are attached in advance, respectively.
One end of the rotor is axially supported on the housing cover 1b via the oil seal 8 and the bearing 7, and the phases of the rotors 3 and 4 are adjusted.

Then, in this state, the gears 10, 11 are loosely inserted from the minimum diameter EMIN side to the shaft ends of the rotor shafts 5, 6 projecting from the housing cover 1b, and the gears 10, 11 are meshed with each other.
The side surface of 11 is brought into contact with the bearing 7, and the shaft ends of the rotor shafts 5 and 6 and the bosses 10a and 11 of the gears 10 and 11 are connected.
A bush 12 is inserted between the bush 12 and the inner surface of a, and the back surface of the bush 12 is tightened with a nut 13 screwed into the shaft ends of the rotor shafts 5 and 6 via a washer 14. Then, the bush 12 receives the pressing force of the nut 13 and the rotor shafts 5, 6
Move along the axis of.

Since the side faces of the gears 10 and 11 are in contact with the bearing 7, the gears 10 and 11 do not incline even when the bush 12 is pressed by the nut 13, and the gears 10 and 11 are not tightened during tightening. The meshing between them does not change, the backlash can be easily controlled, and the assembling accuracy can be improved to reduce the gear meshing noise.

As a result, since the minimum diameter DMIN of the tip of the bush 12 is larger than the minimum diameter EMIN of the inner diameter of the gears 10 and 11, the bush 12 is gradually pressed between the rotor shafts 5 and 6 and the inner surfaces of the gears 10 and 11. Then, the inner diameter D of the bush 12 is contracted by the slit 12b and the bush 12 is fitted therein, and the gears 10 and 11 are fixed to the rotor shafts 5 and 6.

Then, in this state, the housing body 1a is mounted from the other end side of the rotor shafts 5 and 6, and the other end side of the rotor shafts 5 and 6 is pivotally supported by the housing body 1a via the bearing 7.
The housing body 1a and the gear cover 2 are fixed in contact with the housing cover 1b.

Since the gears 10 and 11 are fixed to the rotor shafts 5 and 6 by press-fitting the bush 12 in this manner, sufficient torque can be transmitted without using a conventional key or the like.

(Second Embodiment) FIG. 7 is a sectional view corresponding to FIG. 1 according to the second embodiment of the present invention.

In this embodiment, the maximum diameter DMAXN side of the bush 12 shown in the first embodiment is brought into contact with the bearing 7, and the gear 1
The side surface of 0 (11) is pressed by the nut 13 via the washer 14, and the gears 10 and 11 are fixed to the rotor shafts 5 and 6 by the pressing force of the nut 13.

(Third Embodiment) FIGS. 8 to 10 show a third embodiment of the present invention, FIG. 8 is a sectional view corresponding to FIG. 1, and FIG. 9 is a sectional view of a main part of a gear. FIG. 10 (a) is a side view of the main part of the rotor shaft,
Figure (b) is a side view of the bush.

In this embodiment, the inner surface of the bush 12 is the rotor shaft.
The rotor shaft 5 (6) has an inclined surface 12c that widens in the axial center direction of the shaft 5, 6 and has an inclined surface 5a that engages with the inclined surface 12c of the bush 12 at the shaft end portion of the rotor shaft 5 (6). (6a) is formed.

Regarding the dimensions of each portion, the inner diameter E of the boss 10a (11a) of the gear 10 (11) is formed to be slightly larger than the outer diameter D of the bush 12 (E> D).

The inclined surface 12c of the bush 12 and the inclined surface 5a (6a) of the rotor shaft 5 (6) have the same inclination angle, and the inclined surface 5a of the rotor shaft 5 (6) is further increased.
The maximum diameter dMAX of (6a) is formed slightly larger than the maximum diameter DMAX of the inclined surface 12c of the bush 12, and the minimum diameter dMIN of the inclined surface 5a (6a) of the rotor shaft 5 (6) is smaller than that of the bush 12. It is formed larger than the minimum diameter DMIN of the inclined surface 12c (dMAX> DMAX, dMIN> DMIN).

Further, the outer diameter D of the bush 12 and the maximum shape D of the inclined surface 12c
The difference from MAX is formed slightly larger than the difference between the inner diameter E of the gear 10 (11) and the maximum diameter dMAX of the inclined surface 5a (6a) of the rotor shaft 5 (6) (D-DMAX> E-dMA
X).

When the back surface of the bush 12 is pressed by the nut 13 via the washer 14, the bush 12 is expanded along the inclined surface 5a (6a) formed at the shaft end of the rotor shaft 5 (6), This shaft end and the boss 10a of the gear 10 (11)
It is fitted between the inner surface of (11a) and the above gear 10 (11).
Is fixed to the rotor shaft 5 (6) by a shaft,
The same effect as the first embodiment can be obtained.

The expansion of the bush 12 is allowed by the slit 12c formed on one side of the bush 12.

[Advantages of the Invention] As described above, according to the present invention, in the roots-type pump in which rotor shafts that respectively support a pair of rotors installed in a rotor housing are connected to each other via gears, Since a bush having a wedge-shaped cross section is press-fitted between the rotor shaft and the hub of the gear inserted through the rotor shaft, the gear is axially attached to the rotor shaft by press-fitting the bush during assembly. be able to. Therefore, phase alignment between rotors and meshing adjustment between gears are facilitated, mass productivity is excellent, and high assembly accuracy can be obtained without increasing processing accuracy, resulting in low noise, low vibration, An excellent effect such as reduction of power loss can be achieved.

[Brief description of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is an enlarged view of part I of FIG. 5, FIG. 2 (a) is a sectional view of a main part of a gear, and FIG. 2 (b). ) Is a sectional view taken along the line II-II of FIG. 3, FIG. 3 is a front view of the bush, FIG. 4 is a side view of the bush, FIG. 5 is a sectional view of the roots type pump, and FIG. 6 is VI of FIG. -VI sectional view, FIG. 7 is a sectional view corresponding to FIG. 1 according to the second embodiment of the present invention, FIGS. 8 to 10 show a third embodiment of the present invention, and FIG. 8 is FIG. Corresponding sectional view, FIG. 9 is a sectional view of the main part of the gear, and FIG. 10 (a) is a side view of the main part of the rotor shaft.
Figure (b) is a side view of the bush. 1 ... Rotor housing, 3,4 ... Rotor, 5,6 ... Rotor shaft, 10,11 ... Gear, 12 ... Bushing.

Claims (1)

[Scope of utility model registration request] 1. A roots-type pump in which rotor shafts for axially supporting a pair of rotors housed in a rotor housing are connected to each other via gears, and the rotor shaft and the rotor shaft inserted into the rotor shaft. A roots-type pump characterized in that a bush having a wedge-shaped cross section is press-fitted between the gear and the gear.