......DE....FRGB..IT......SE......................
C
0085248
EUROPEAN PATENT APPLICATION
A1
19830810
EP
82306811.9
19821220
en
en
en
207322/81
19811221
JP
207323/81
19811221
JP
208745/81
19811223
JP
19830810
198332
19830810
198332
3
3F 04C 15/00 A
3F 04C 2/04 B
de
Verdrängermaschine von Umlaufkolbentyp mit innerem Ausgleichsgewicht
en
Orbiting piston type fluid displacement apparatus with internal balanceweight
fr
Appareil à déplacer un fluide du type à piston rotatif avec une masse d'équilibrage interne
SANDEN CORPORATION
00509720
CHP/11736
20 Kotobuki-cho
Isesaki-shi Gunma-ken
JP
Hiraga, Masaharu
8-34 Honjo 4-chome
Honjo-shi Saitama-ken
JP
Pritchard, Colin Hubert
et al
00035001
Mathys & Squire 100 Grays Inn Road
London WC1X 8AL
GB
DE
FR
GB
IT
SE
An orbiting piston type fluid apparatus is disclosed. The apparatus includes a housing having a casing (11) with a cylindrical inner surface and a front end plate covering an end opening to the casing. A cylindrical core member (20) is carried in the center portion of the casing (11) and has an outer surface concentric with the inner surface of the casing (11). A blade (14) extends axially between the casing (11) and the core member (20). An orbiting cylindrical member (23) is carried for orbital motion within the annular space between the inner surface of the casing (11) and the outer surface of said core member (20) by eccentric crank portions of a drive shaft (17). The core member has a hollow space (201) at its center portion and a balanceweight (27) is assembled on the drive shaft (17) within the hollow space (201).

Background Of The Invention
This invention relates to a fluid displacement apparatus, and more particularly, to a fluid displacement apparatus of the orbiting piston type for use as a supercharger for an engine or as an air compressor.
There are several type of fluid apparatus capable for use as air pumps or compressors. One well known machine is a velocity type compressor or blower which can handle a large air flow due to the high rotational speed of a fan blade. Another type of fluid apparatus is the fluid displacement apparatus, for example a piston- type fluid apparatus or a rotary vane type fluid apparatus, which can handle large pressure of fluid due to the enclosure of the fluid within a cylinder, and its discharge against the pressure at a discharge side.
These two types of the fluid apparatus are respectively used for specific purposes. However, these two types of fluid apparatus have the various advantages and disadvantages, i.e., a velocity type apparatus can handle a large air flow but is not particularly suitable for high discharge pressure, while a fluid displacement apparatus has the reverse advantage and disadvantage.
The supercharger for an engine, which is designed to increase the output of the engine by supercharging the suction air, must have intermediate character between the velocity type apparatus and fluid displacement apparatus, i.e. compress air at about _0._5 pressure above atmospheric pressure, and handle an air flow at _5-iom^3/min. Furthermore, the supercharger must be compact and lightweight, because the supercharger is preferably located within the engine compartment, which is already designed, without any influence on the other mechanisms connected with the engine. In prior superchargers, which have been driven by the engine through a rotation transmitting device, for example, a gear or belt, the output of the engine, which is improved by the supercharging of supercharger, has generally not been sufficiently large to drive the supercharger. The supercharger is usually driven over a large range of rotational speeds, so that both high volume efficiency and total pressure efficiency have not been attained. Furthermore, the supercharger requires a change over device to control the supercharging and non-supercharging operations, as occasion demands however, prior mechanisms which have controlled the change over device have not attained smooth change over operation.

Summary Of The Invention
It is a primary object of this invention to provide an improved orbiting piston type fluid apparatus having a large range of the rotational speeds and long life.
It is another object of this invention to provide an orbiting piston type fluid apparatus with increased volume efficiency and total pressure efficiency.
It is a further object of this invention to provide an orbiting piston type fluid apparatus having a changeover device to control the operation of the apparatus.
It is still another object of this invention to provide an orbiting piston type fluid apparatus with improved dynamic balance so that vibration of the apparatus is reduced.
It is yet another object of this invention to provide an orbiting piston type fluid apparatus which is simple to construct and can be simply and reliably manufactured.
An orbiting piston type fluid apparatus according to this invention includes a housing having a cylindrical casing and a front end platc, attached to one end opening of the casing. A cylindrical core member is located in the center portion of the casing and has an outer surface concentric with the inner surface of the casing.
A blade axially extends within the space between the casing and core member. An orbiting cylindrical member is disposed in an annular space defined between the inner surface of the casing and the outer surface of the core member to form a working fluid chamber, and has a slot for passage of the blade in a radial direction. A drive shaft is rotatably supported by the housing at both end portion thereof. The orbiting cylindrical member is supported .for orbital motion by eccentric crank portions disposed on both end portions of the drive shaft, which carry the orbiting cylindrical member through bearings. The core member has a hollow space at its center portion. A balanceweight which cancels the unbalance caused by the orbital motion is assembled on the drive shaft within the hollow space of the core member.
Further objects, features and aspects of this invention will be understood from the following detailed description of preferred embodiments of this invention, referring to the annexed drawings.

Brief Description Of The Drawings
- Figure i is schematic perspective view of an orbiting piston type fluid displacement apparatus according to this invention;
- Figure _2 is a vertical sectional view of the orbiting piston type fluid displacement apparatus shown in Figure I;
- Figure _3 is a vertical sectional view taken along line III-III in Figure 2;
- Figure _4 is a vertical sectional view taken along line IV-IV in Figure _2;
- Figure _5 is a vertical sectional view taken along line V-V in Figure _2;
- Figure 6 is a perspective view of the cylindrical orbiting member shown in Figure _2;
- Figure _7 is a perspective view of a cylindrical orbiting member according to another embodiment of this invention;
- Figure 8 is a vertical sectional view of an orbiting piston type fluid displacement apparatus according to another embodiment of this invention;
- Figure 9a-9h are schematic views illustrating the relative movement of cylindrical orbiting member shown in Figure _2;
- Figure 10 is a vertical sectional view of an orbiting piston type fluid displacement apparatus according to a further embodiment of this invention;
- Figure 11 is a vertical sectional view of an orbiting piston type fluid displacement apparatus according to another embodiment of this invention;
- Figure _{12} is a vertical sectional view of an orbiting piston type fluid displacement apparatus according to another embodiment of this invention;
- Figure I3 is a schematic perspective view of the cylindrical orbiting member shown in Figure _{12};
- Figure _{14} is a perspective view of the crank member for a rotation preventing device shown in Figure _{12}; and
- Figure 15a is a partially sectional view of the orbiting piston type fluid displacement apparatus shown in Figure 12; and
- Figure 15b is an enlarged detail view of portion A in Figure 15a.

Detailed Description Of The Preferred Embodiments
Referring to Figures _I and _2, an embodiment of a fluid apparatus in accordance with the present invention, in particular an orbiting piston type apparatus _I is shown. Apparatus i includes a housing 10 having a cylindrical or cup shaped casing 11 with one end opening closed by an end plate member 111. A front end plate _{12} is attached to other end opening of cylindrical casing 11 by a plurality of bolts _{13}. The end openings of cylindrical casing 11 are thus covered by end plate member 111 and front end plate 12 to seal off the inner chamber of casing 11. A rectangular shaped projection 112 projects from the outer peripheral surface of cylindrical casing 11 and extends from the front end portion of the casing 11 to its rear end portion to form a rectangular opening. A blade or partition _{14} is located within the rectangular opening and extends axially to define a suction port 15 and discharge port _16 within the opening. Each longitudinal end of partition _{14} is attached to projection 112.
An opening 121 is formed in the center of front end plate _{12} for passage or penetration of a drive shaft _{17}. An annular sleeve _{122} projects from the front end surface of front end plate _{12} and surrounds drive shaft _{17}. The outer end of drive shaft _{17} which extends from sleeve _{122} is connected to a rotation transmitting device which may be disposed on the outer peripheral surface of sleeve 122 for transmitting rotational movement to drive shaft _{17}.
Drive shaft _{17} is rotatably supported by front end plate _{12} and end plate member 111 of cylindrical casing 11 through two bearings _18 and 19. Bearing _18 is located within opening 121 of front end plate _{12} and the other bearing _{19} is located within an annular depression 113 of end plate member 111. A cylindrical core member _{20} is arranged on and around drive shaft _{17}, and supported by drive shaft _{17} through bearings _{21} and _{22}. The outer peripheral surface of cylindrical core member _{20} is concentric with the inner surface of cylindrical casing 11. Cylindrical core member _{20} has a cylindrical cavity 201 at its center portion and two supporting members _{202} and _{203} at both end portions of cylindrical cavity _{201}. Supporting members _{202} and _{203} extend radially inward from the inner surface of core member _{20} and are supported on drive shaft _{17} through bearings _{21} and _{22}. Furthermore, the inner end portion of blade _{14} is fixed on the outer peripheral surface of cylindrical core member _{20}, as shown in Figure _3, to fixedly locate it within the inner chamber of cylindrical casing 11. As shown in Figure _2, one supporting member, support member _{202}, is formed separately from the cylindrical core member _{20} and is fitted in the inner surface of cylindrical core member _{20}. Alternatively, cylindrical core member _{20} may be fixed by blade _{14} alone, as shown in Figure 11, or supported by one supporting member _{204} formed in the center portion of its inner wall, as shown in Figure 10.
Drive shaft 17 has two eccentric crank portions 171 and 172 attached at both end portions of drive shaft 17 and located in the same angular postion. Eccentric crank portion 171, which is located closest to front end plate _{12}, is formed separately from drive shaft 17 and fixed on drive shaft 17 by a key 211. An orbiting cylindrical member _{23} is disposed within the inner chamber of cylindrical casing 11 and surrounds cylindrical core member 20. One end opening of orbiting cylindrical member _{23} is closed by block end plate _{231}, and the other by block end plate _{232}. The orbiting cylindrical member _{23} is supported by drive shaft _{17} through crank portions 171 and _{172} and two bearings _{24} and _{25} which are located between the outer peripheral surfaces of crank portions 171 and 172 and the inner peripheral surfaces of end plates _{231} and _{232}. Orbiting cylindrical member _{23} has an axially extending slot _{233} to prevent interference between orbiting cylindrical member _{23} and blade _{14} during the orbital motion of orbiting cylindrical member _{23}. As shown in Figure _2, the front block end plate _{231} is formed separately from orbiting cylindrical member _{23} to permit the insertion of core member _{20}. Front block end plate _{231} is fixed on the end portion of orbiting cylindrical member _{23} by any suitable conventional technique.
A rotation preventing device _26 is located between the inner end surface of front end plate _{12} and the axial end surface of block end plate _{231} of orbiting cylindrical member _{23}. Rotation preventing device _26 includes an orbiting ring _26_1 which is fastened against the end surface of block end plate _{231}, a fixed ring _26_2 which is fastened against the inner end surface of front end plate _{12}, and bearing elements, such as a plurality of spherical balls _26_5. Both rings _26_1 and _26_2 have a plurality of pairs of adjacent circular indentations or holes _26_3 and _26_4. As shown in Figure _2, both rings _26_1 and _26_2 are formed of separate plate elements _26_1a and _26_2a, each of which are respectively fixed on an end surface by pins _266 (Fig. _4), and ring elements _26ib and _26_2b which have the plurality of pairs of holes _26_3 and _26_4. Alternatively, the plate and ring elements may be formed integral with one another. In operation, the rotation of orbiting cylindrical member _{23} is prevented by balls _26_5, which interact with the edges of holes _26_4 and 26.3 to prevent the rotation. In the embodiment shown by Figure _2, rotation preventing device _26 is located between the inner surface of front end plate _{12} and one end surface of orbiting cylindrical member _{23}. However, as shown in Figure 8, another rotation preventing device _26' may be located between an inner surface of end plate member 111 of casing 11and other end surface of orbiting cylindrical member _{23} to prevent twisting of orbiting cylindrical member. If rotating motion of orbiting cylindrical member _{23} is prevented by only one rotation preventing device located between the first end plate and one end surface of orbiting cylindrical member _{23}, the other end portion of orbiting cylindrical member _{23} is free to rotate, so that twisting motion may be caused.
A balanceweight _{27} is fixed on drive shaft _{17} by a key _28 and is disposed within a cylindrical cavity of core member _{20} to hold the dynamic balance of the apparatus. The centroid of balanceweight _{27} is angularly offset 180° from the angular location of eccentric crank portions _{171} and _{172}. In order to further enhance dynamic balance, cut-out portions _26_7 are formed in orbiting ring _26_1 as shown in Figure _7, to coincide the centroid of the orbiting cylindrical member _{23} with the axis of drive shaft _{17} since the orbiting cylindrical member _{23} is formed with slot _{233}, which would cause an unbalance.
In this construction of the fluid apparatus, the parts which define the working chamber of the apparatus move through a noncontacting point with respect to one another, i.e., a gap between the outer surface of core member 20 and the inner wall surface of orbiting cylindrical member _{23}, and a gap between the inner surface of cylindrical casing 11 and the outer wall surface of orbiting cylindrical member _{23} are created with minimum clearance to prevent interference of the parts caused by the eccentricity of the parts which results in manufacturing.
The axial positioning of the two bearings _{21}, _{22} and one crank portion 171 is maintained by spacers _{177} and _{179} which are disposed on the drive shaft _{17}. The axial movement of orbiting cylindrical member _{23} is absorbed by a spring washer _{175} located between the crank portion 172 and bearing 19.
The principle of operation of a typical orbiting piston type fluid apparatus will be described with reference to Figures 9a-9h.
In Figure _9a, the longitudinal axis of the eccentric crank portion is shown at its top vertical position or at 0°. The point of tangency Q_4 between the inner wall surface of orbiting cylindrical member _{23} and the outer peripheral surface of core member _{20} defines an inner fluid chamber B which has two sections, each extending from the point of tangency to opposite side of blade _{14}. In this stage, an outer fluid chamber A, which extends substantially from one side of blade 14 to the other, is also formed between the outer wall surface of orbiting cylindrical member _{23} and the inner wall of cylindrical casing 11. Figure gb shows the state of the orbiting cylindrical member _{23} at a drive shaft crank angle which is advanced a° from that in Figure _9a. In this state, a point of tangency Pi between the outer wall surface of right end portion of orbiting cylindrical member _{23} and the inner wall of cylindrical casing 11 is formed, therefore the outer fluid chamber A is sealed off. However, a clearance between the outer wall surface of left end portion of orbiting cylindrical member _{23} and the inner wall of cylindrical casing 11 is created, so that outer fluid chamber A is connected with the discharge port 15 through the clearance. The fluid in outer fluid chamber A is discharged through the clearance due to reduction of volume of outer fluid chamber A which is caused by the further orbital motion of orbiting cylindrical member _{23}, as shown in Figures 9c-9f. On the opposite side of the point of tangency P, (Pi-P6), a new chamber A' is formed to take in fluid.
During the discharge of fluid within outer fluid chamber A, the volume of inner fluid chamber B is increased to take in fluid, as shown in Figure ga-_9d. When the inner wall surface of right end portion of orbiting cylindrical member _{23} contacts the outer wall surface of core member _{20}, the inner fluid chamber B is sealed off, as shown in Figure _9f, and simultaneously connected with the discharge port _{15} through a clearance between the left end portion of orbiting cylindrical member _{23} and core member _{20}. The volume of the inner fluid chamber B is gradually reduced due to further orbital motion of member _{23}, as shown in Figures _9a-_9c. The discharging of fluid within the inner fluid chamber B thus continues until the inner wall surface of left end portion of orbiting cylindrical member _{23} contacts the outer wall surface of core member _{20}. On the opposite side of point of tangency Q,(Q1~Q7), a new inner fluid chamber B' is formed to take in fluid.
In such operation, suction port _{15} is in fluid communication with discharge port _16 while passing the stages from Figure gh to Figure _9b, and also while passing the stages from Figure 9d to Figure 9f. This occurs because while passing the stages from Figure gh to Figure 9b, clearance between the outer wall surface of both end portions of orbiting cylindrical member _{23} and the inner surface of cylindrical casing 11 is created; and also while passing the stages from Figure _9d to Figure _9f, clearance between the inner wall surface of both end portions of orbiting cylindrical member _{23} and the outer surface of core member _2o is created. However, if the angular aperture 2° of slot _{233} is designed to a set minimum degree without interference between orbiting cylindrical member _{23} and blade _{14}, the apparatus can operate at a pressure ratio i or _2 without causing problems. Furthermore, the apparatus can be made with an orbiting cylindrical member having a comparatively small radius, so that the apparatus can be operated at high speeds without expending great energy to thereby shorten the time during which the suction and discharge ports are connected.
In comparison with rotary apparatus which include a rotatable piston member, inertia moment of the moving parts of this apparatus will be smaller; the suction side and discharge side is penetrated by two cylindrical members of close curvature, and transfer of the air due to the rotation of the drive shaft does not result in shearing of the air, therefore, this apparatus can be operated at high speed.
Referring to Figures _{12}-_{15}, another embodiment is shown. This embodiment is directed to a modification of the orbiting cyiin- drical member to improve the volumetric efficiency by filling in the gap between the axial end surface of the blade and the opposite surface as far as possible. In this embodiment, an annular axial projection _{233} extends from the center portion of axial end surface of front block end plate _{231}, and a radial flange portion 234 extends radially outward from the outer end portion of annular projection _{233}. Radial flange portion _{234} thus is located at an axially spaced distance from the front end surface of front block end plate _{231}. The outer diameter of radial flange portion _{234} is formed the same as outer diameter of orbiting cylindrical member _{23}. An annular plate _{29} is fixed on one end surface of casing 11, and extends radially inward into the space between flange portion _{234} and block end plate 23t
A rotation preventing device _{30}, for example, a crank type coupling mechanism is located between the inner surface of front end plate _{12} and an end surface of radial flange portion _{234}. In this embodiment, rotation preventing device _{30} includes a plurality of cranks 301, as shown in Figure _{14}, and pairs of adjacent circular indentations 302 and _{303} formed on the front end plate _{12} and radial flange portion _{234}. Crank shaft portions _{30}ia and _{30I}b of crank _{301} are inserted into indentations 302 and _{303} to permit smooth orbital movement without rotation. Bearings _{305} are preferably interposed between crank shaft portions _{30}ia, _{30I}b and indentations _{302} and 303.
In this construction, the gap between the axial end surface of the blade and the fixed element 20 which defines the working chamber, is formed smaller, thus improving the volumetric efficiency.
Furthermore, as shown in Figure _{15}, an annular groove _{32} is formed on the axial end surface of block end plate _{231} and a seal element _{33} is placed within groove _{32}. The area containing the working space can be partitioned from the space containing the rotation preventing device _{30} which may be lubricated. The grease therefore can be enclosed in the space containing the rotation preventing device.
This invention has been described in detail in connection with preferred embodiments, but these are examples only and this invention is not restricted thereto. It will be easily understood by those skilled in the art that the other variations and modifications can be easily made within the scope of this invention.
1. In an orbiting piston type fluid apparatus including a housing having a casing with front and back end portions and a cylindrical inner surface extending between the end portions, a front end plate attached to an opening in the front end portion of said casing, a cylindrical core member disposed in a center portion of said casing and having an outer surface concentric with the inner surface of said casing, a blade extending axially between said casing and core member, an orbiting cylindrical member disposed in an annular space defined between the inner surface of said casing and the outer surface of said core member to form a working fluid chamber and having a slot for passage said blade in a radial direction, a drive shaft having front and back end portions rotatably supported by said housing at both end portions thereof, and eccentric crank portions disposed on both end portions of said drive shaft for carrying said orbiting cylindrical member in an orbital motion through bearings located on the outer surface of said crank portions, the improvement comprising said core member having a hollow space at the center portion thereof and a balanceweight assembled on said drive shaft within said hollow space for cancelling unbalance caused by the orbital motion of said orbiting cylindrical member.
_2- The orbiting piston type fluid apparatus of claim i wherein said casing has a projection which extends axially from the front end portion to a back end portion of said casing and forms a rectangular opening in said casing, said blade being disposed within the opening of said projection to partition the opening into a suction port and a discharge port, and said blade having one end portion fixed on said core member.
_3. The orbiting piston type fluid apparatus of claim _2 wherein said core member has a supporting portion projecting radially from its inner wall and supported by said drive shaft through a bearing 1 located between said drive shaft and said supporting portion.
_4. The orbiting piston type fluid apparatus of claim further comprising a rotation preventing device disposed between the inner surface of said front end plate and an end surface of said orbiting cylindrical member to prevent the rotation of said orbiting cylindrical member during its orbital motion.
_5. The orbiting piston type fluid apparatus of claim _4 wherein a further rotation preventing device is disposed between the end surface of said casing at its back portion and the end surface of said orbiting cylindrical member adjacent thereto.
6. The orbiting piston type fluid apparatus of claim _4 or _5 wherein said rotation preventing device comprises a plurality of pairs of circular indentations formed on the end surfaces of said housing and said orbiting cylindrical member and a plurality of spherical balls carried in facing pairs of indentations.
_7. The orbiting piston type fluid apparatus of claims _4 or _5 wherein said rotation preventing device comprises a plurality of crank members each of which has an eccentrical pin on each side thereof, and pairs circular indentations formed on the end surfaces of said housing and orbiting cylindrical member into which the pins of said crank are inserted.
8. The orbiting piston type fluid apparatus of claim 8 further comprising a bearing disposed between each of the pins of said crank members and the circular indentation within which it is inserted.
_9. The orbiting piston type fluid apparatus of claim i or _4 wherein said orbiting cylindrical member has block end plate at both of its end portions to cover the opening thereof, and said block end plates being carried on said bearings which are located on the outer surface of said crank portion.
_{10}. The orbiting piston type fluid apparatus of claim _9 wherein one of said block end plates which faces said front end plate has an axial projection from which a radial flange extends and faces the end surface of said last-mentioned block end plate at an axially spaced distance, a rotation preventing device is located between the inner surface of said front end plate and said radial flange, and an annular plate is located between said radial flange and said last mentioned block end plate.
11. The orbiting piston type fluid apparatus of claim 10 wherein said block end plate which is adjacent to said annular plate has an annular groove, and seal element is disposed within said groove to seal off the gap between said last-mentioned block end plate and said annular plate.
12. The orbiting piston type fluid apparatus of claim 10 wherein said rotation preventing device comprises a plurality of pairs of circular indentations formed on the end surfaces of said housing and said orbiting cylindrical member and a plurality of spherical balls carried in facing pairs of indentations.
_{13}. The orbiting piston type fluid apparatus of claim 10 wherein said rotation preventing device comprises a plurality of crank members each of which has an eccentric pin at each side thereof, and pairs circular indentations formed on the end surfaces of said housing and said orbiting cylindrical member into which the pins of said crank are inserted.
_{14}. The orbiting piston type fluid apparatus of claim _{13} further comprising a bearing disposed between each of the pins of said crank members and the circular indentation within which it is inserted.