JPH0249992A - Roots blower - Google Patents

Abstract

PURPOSE:To restrain loss due to leakage in a supercharger for automobile engine or the like, by setting the amount of escape of rotating direction side intake air pressure-feed surfaces between a drive rotor and a driven rotor in a Roots blower, which are rotated reversely to each other in a non-contact condition within a hosing, to a value which is greater than that of the other intake air pressure-feed surfaces. CONSTITUTION:Drive rotor 2 and a drive rotor 3 which are cocoon shapes are rotated by a pair of gears which are not shown, around a drive shaft 6 and a driven shaft 7 as indicated by the arrows A in reverse directions but in synchronization with each other under a non-contact condition, that is, a Roots blower is constituted. The amount of air-escape between rotating direction side intake-air pressure-feed surfaces 14, 16 is set to a value which is greater than that between the opposite side intake-air pressure-feed surfaces 13, 15 so as to increase the amount of escape between the rotors only in a part which has a risk of a bump between the rotors. With this arrangement it is possible to effectively restrain the leakage of suction air, thereby it is possible to prevent the rotors to making contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a roots-type floor used as a supercharger for an automobile engine or the like.

[Prior Art] This type of blower has a cocoon-shaped drive rotor and a driven rotor of the same shape facing each other and are pivoted in a housing, and both rotors are connected to a pair of gears by engine power. There is a known device in which the rotors are rotated synchronously in opposite directions via the rotor. However, since this type of blower is a non-contact type, it is desirable that the gap between the drive rotor and the driven rotor be as small as possible, and it is essential that the phase between the rotors be maintained with high precision. . However, in reality, as prior art to the present invention, for example, as shown in Japanese Unexamined Patent Application Publication No. 60-75793, errors in machining and assembly of each component are expected, and the suction pressure of the drive rotor and driven rotor is A relief amount is provided on the surface to increase the gap.

[Problems to be Solved by the Invention] However, in the conventional system, the amount of relief is provided at a constant ratio in the drive rotor and the driven rotor, and the amount of relief is provided at a constant ratio between the intake pressure feeding surface on the rotation direction side and the intake pressure feeding surface on the opposite side. are usually symmetrically formed. Therefore, if slipping occurs between the gear and the shaft or wear occurs on the gear and the drive rotor and driven rotor are out of phase, the rotor will shift due to the amount of relief described above if the two rotors are approximately perpendicular to each other. Contact between the two rotors can be avoided, but if the two rotors are in a non-orthogonal state, the intake pressure delivery surface on the rotational side of the drive rotor and the intake pressure delivery surface of the driven rotor that faces this intake pressure delivery surface rapidly approach each other. There is a high risk of contact. Furthermore, if the amount of escape is simply increased, the gap between the drive rotor and the driven rotor will increase, which will increase the leakage loss of intake air and reduce the filling efficiency.

The present invention aims to eliminate such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a drive rotor and a driven rotor that are pivotally mounted in a housing without contacting each other, and a pair of gears that connect the drive rotor and the driven rotor. In a Roots-type blower configured to rotate synchronously in opposite directions via the drive rotor, a relief between an intake pressure feeding surface on the rotation direction side of the drive rotor and an intake pressure feeding surface of the driven rotor facing the intake pressure feeding surface. It is characterized in that the amount of relief is larger than the amount of relief on the other suction pumping surfaces of each of the rotors.

[Function] With this configuration, the amount of relief is increased on the intake pressure feeding surface on the rotational direction side of the drive rotor and the intake pressure feeding surface of the driven rotor that faces this intake pressure feeding surface, and the amount of relief is increased on the opposite side. In terms of intake pressure, the amount of escape is suppressed as much as possible. Therefore, even if there is a phase error between the drive rotor and the driven rotor, it becomes difficult for the drive rotor and the driven rotor to come into contact with each other, and leakage loss is suppressed.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 2, the roots-type blower shown in the drawings houses a drive rotor 2 and a driven rotor 3 in a housing 1 facing each other in a non-contact state, and these rotors 2.3 are driven by engine power. Drive gear 4 and driven gear 5
The drive rotor 2 and driven rotor 3 are supported by the housing 1 via a drive shaft 6 and a driven shaft 7, respectively.

The housing 1 includes a housing main body 1a having an oval cross section;
It consists of a partition wall 1b that divides the space within the housing body 1a into a pump chamber 8 and a gear chamber. The drive shaft 6 has both ends (one end not shown) and an intermediate part connected to the housing body 1a and the partition wall 1 via bearings 10.
b. The drive gear 4 is attached to a portion of the gear chamber 9, and a pulley 11 is fixed to an end that penetrates the housing body 1a and projects to the outside. The driven shaft 7 has both ends (
One end (not shown) is supported by the housing body 1a and the partition wall 1b via bearings 12, respectively. Further, the driven gear 5 having the same size as the drive gear 4 is fixed to the end portion which penetrates the partition wall 1b and projects into the gear chamber 9, and is meshed with the drive gear 4.

The drive rotor 2 is cocoon-shaped and is held by the housing body 1a and the partition wall 1b without contacting the inner wall surface 8a of the pump chamber 8 via the drive shaft 6 press-fitted into the through hole in the shaft center. be.

The driven rotor 3 is cocoon-shaped and has the same size as the drive rotor 2. The driven rotor 3 is attached to the inner wall surface 8a of the pump chamber 8 in a non-contact state through the driven shaft 7 press-fitted into a through hole in the axial center of the housing. It is held by the main body 1a and the partition wall 1b. When engine power is input through a belt stretched between the pulley 11 and a crank pulley, the drive rotor 2 and the driven rotor 3 rotate at a constant speed in opposite directions without contacting each other. The well-known pumping action is carried out by this.

Therefore, the intake pressure feeding surface 13.1 of the drive rotor 2
4 and the profiles of the suction pressure and delivery surfaces 15 and 16 of the driven rotor 3 are determined by taking into account machining errors and assembly errors of the blower components. For example, both rotors 2.3 are 4
In the case of a combination of an epicycloid and a hypocycloid that coincide on a 5° line, let X be the minor axis, y be the major axis, and R be the radius of the major axis of both rotors 2.3.
The /X ibocycloid curves of the drive rotor 2 and the driven rotor 3 are expressed by the following equation.

x-(3/4)Rcosσ-(1/4)Rcos
3αy=(3/4) Rsin++-(1/4
) R5in8α Note that 0≦α≦π/4 On the other hand, the ebicycloid curves of the drive rotor 2 and the driven rotor 3 are expressed by the following equation.

x = (5/4) Rcosα-(1/4) R
cos(5α-1)y = (5/4) Rsi++a
-(1/4) R5in(5α-r) In addition, π/4
≦α≦π/2 In addition to the gap formed between the drive rotor 2 and the driven rotor 3, there is also a gap between the drive gear 4 and the drive shaft 6, and a gap between the driven gear 5 and the driven gear 5. The amount of relief that takes into account the phase error between the two rotors 2 and 3 caused by slipping between the driven shaft 7 or wear between the drive gear 4 and the driven gear 5 is determined by the intake pressure and feed on the rotational direction side of the drive rotor 2. It is provided on the surface 13 and on the suction pumping surface 15 of the driven rotor 3 that faces the suction pumping surface 13. To be more specific, as shown in FIG. 1, when the drive rotor 2 and the driven rotor 3 are perpendicular to each other, even if there is a minute phase error between the two rotors 2 and 3, they will come into contact. Since this rarely occurs, the sum S1 of the relief between both rotors 2.3 in this state is determined by the pitch error in the shaft support portion of the housing 1, the concentricity of the drive shaft 6 and the driven shaft 7, The contour degree of both rotors 2.3 is estimated and set to Δ0.

As shown in FIG. 4, when the drive rotor 2 and the driven rotor 3 are rotated by 45 degrees in the direction of arrow The sum S2 is the aforementioned value Δ. However, taking into consideration that phase errors may occur due to machining errors in the drive gear 4 and the driven gear 5, or errors in the assembly of the drive gear 4 and the driven gear 5 to each shaft 6.7, The sum S2 of the relief amounts of the drive rotor 2 and the driven rotor 3 in this case is Δ. It should be +Δ1. Furthermore, in this case, considering that a phase error occurs between the drive rotor 2 and the driven rotor 3 due to wear of the drive gear 4 and the driven gear 5, the amount of relief at such a position is determined by the rotation of the drive rotor 2. an intake pressure feeding surface 13 on the direction side and an intake pressure feeding surface 1 of the driven rotor 3 opposing this intake pressure feeding surface 13
5 should be (Δ.+Δ1)2+Δ2, respectively. On the other hand, the relief at the intake pressure delivery surface 14.16 on the opposite side of the intake pressure delivery surface 13.15 is Δ. By setting +Δ1)2−Δ2, the clearance between the drive rotor 2 and the driven rotor 3 can be set to the required clearance while preventing it from being increased more than necessary.

According to the relationship described above, the angles of 00145° and 90° 13 of the drive rotor 2 and the driven rotor 3 are respectively
The normal relief at the 5° to 180° positions is determined, and the amount of relief between each angle is made to vary progressively as a function of the respective rotor angle. That is,
The sum of the relief amounts of the intake pressure delivery surface 13 on the rotational direction side of the drive rotor 2 and the intake pressure delivery surface 15 of the driven rotor 3 that faces this intake pressure delivery surface 13 is Δ at the 90° position of both rotors 2.3. , at the 45° position of each rotor 2.3 Δ
. +Δ1) +Δ2Z, so the sum of these relief amounts is Δ. , /Tτ0 + a 1-cho2+Δ22 is distributed equally to the drive rotor 2 and the driven rotor 3, the amount of relief at the concave portion (0°) of each rotor 2.3 is:
Δ respectively. /2, and the relief amount at the 45° position is (Δ. 1 Δ1) 1 Δ22)/2, respectively. Then, the rotation angle between 06 and 45'' of each rotor 2.3 is set to θ(
d e g), and if the amount of relief during this period is changed quadratically, the relief of each rotor 2.3 at 00 to 45 degrees is expressed by the following equation.

δ5x=1/2 ((Δ0+Δ1)2+Δ22Δo
〉(θ/45) 'Similarly, the escape angle δ between 45° and 90° is 2.90°
Relief amount δ at ~135°, 3.135° ~ 180°
The relief capacitors δ and 4 in are as follows.

δ52=1/21 (Δ.−Δ.+Δ1) +Δ2)(
θ/45)ffi+Δ0+Δ1)Tτ7)・δ−3=1/2i (Δ.+Δ1)2−Δ22−Δ. )
(θ/45)'+Δ. ) δea=1/z((Δ.−Δ.+Δ1) −τ77)(
θ/45) q+, /Tτ, +A1) −Δ2′) Note that m, n, p, and q are each positive real numbers.

By appropriately selecting these values, the relief at each position of the intake pressure delivery surface 13 on the rotational direction side of the drive rotor 2 and the intake pressure delivery surface 15 of the driven rotor 3 facing this intake pressure delivery surface 13 can be adjusted. I'm trying to adjust it.

According to such a configuration, the amount of relief between the intake pressure feeding surface 13 on the rotational direction side of the drive rotor 2 and the intake pressure feeding surface 14 on the opposite side of this intake pressure feeding surface 13 is different,
The intake pressure feeding surface 16 on the rotation direction side of the
The amount of relief from the intake pressure feeding surface 15 on the opposite side is different from each other.

Therefore, when the drive rotor 2 and the driven rotor 3 are in a perpendicular state, the gap between the two rotors 2 and 3 is made as small as possible, so that leakage loss of intake air in such a state is suppressed. Ru. When the intake pressure feeding surface 13 on the rotational direction side of the drive rotor 2 and the intake pressure feeding surface 15 of the driven rotor 3 are in an opposing state, the gap between both rotors 2.3 increases by a minute dimension, and the driven rotor When the intake pressure feeding surface 16 on the rotational direction side of the rotor 3 and the intake pressure feeding surface 14 of the drive rotor 2 corresponding to this intake pressure feeding surface 16 are in an opposing state, the gap between both rotors 3.2 is minute. Dimensions.

Therefore, according to such a configuration, the drive rotor 2 may be damaged due to slippage between the drive gear 4 and the drive shaft 6, between the driven gear 5 and the driven shaft 7, or due to wear of the drive gear 4 and the driven gear 5. Even if a phase error occurs later between the drive rotor 2 and the driven rotor 3, the drive rotor 2
This can effectively prevent the driven rotor 3 from coming into contact with the driven rotor 3. Moreover, according to such a device, the relief amount is increased only in the portion where there is a high possibility that the rotors 2.3 will come into contact with each other due to a phase shift between the two rotors 2.3. Compared to the case where the amount of relief is uniformly expanded and provided, leakage loss of intake air can be suppressed, and problems that degrade the pump function can be prevented.

It goes without saying that the profiles of the drive rotor and the driven rotor are not limited to the values shown in the above embodiments. Further, the drive rotor and the driven rotor are not limited to those having a cocoon shape, but may have a trilobal cross section.

[Effects of the Invention] As described above, in the present invention, the amount of clearance of the rotors is increased only in the areas where the rotors are likely to come into contact with each other.
It is possible to provide a roots-type blower with excellent reliability that can effectively prevent contact between rotors while effectively suppressing leakage loss of intake air.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory diagram of a rotor profile, FIG. 2 is a vertical cross-sectional view showing a roots-type blower with a portion omitted, and FIG. 3 is a section A in FIG. 1. FIG. 4 is a diagram showing a state in which the rotor is rotated by a certain angle, and FIG. 5 is an explanatory diagram of section B in FIG. 4. 1... Housing 2... Drive rotor 3... Driven rotor 4... Drive gear 5... Driven gear 13.14... Intake pressure feeding surface 15.16... Intake pressure feeding surface

Claims (1)

[Claims] A roots-type blower configured to have a drive rotor and a driven rotor pivoted in a housing without contacting each other, and to rotate the drive rotor and driven rotor synchronously in mutually opposite directions via a pair of gears, The amount of relief between the intake pressure feeding surface on the rotational direction side of the drive rotor and the intake pressure feeding surface of the driven rotor facing the intake pressure feeding surface is made larger than the amount of relief on the other intake pressure feeding surfaces of each of the rotors. A characteristic roots-type blower.