Patent Description:
There has been known an oil separator that separates mist oil contained in target gas from the gas. For example, an oil separator described in Patent Literature <NUM> includes a cylindrical stationary housing, a cylindrical stationary casing with a ceiling, and a conical partition with an opening on the top surface. These components define a lower chamber and an upper chamber. The lower chamber includes a centrifugal rotor to clean oil. The upper chamber includes a gas cleaning device to clean gas. A lower end of the stationary housing is coupled to a base. The lower chamber is communicated with an internal space of the tubular base.

This tubular base is communicated with a combustion engine. Oil after being cleaned is returned to the combustion engine and gas from a crankcase is introduced to the combustion engine. In the internal space of the tubular base, a tubular fixing member is disposed which fixes the lower end of the shaft. Through the fixing member, oil to be cleaned is supplied.

The centrifugal rotor and the gas cleaning device are coupled with a tubular supporting member and are rotatable around a stationary shaft inserted through the supporting member. The centrifugal rotor internally includes a separation chamber. The oil is supplied to this separation chamber through a clearance between the supporting member and the stationary shaft and through an opening open at the supporting member. After the cleaning in the separation chamber, the supplied oil is discharged to a side portion through discharge ports disposed at a bottom surface of the centrifugal rotor. Discharging the oil generates a driving power to rotate the centrifugal rotor and the gas cleaning device.

Another example of such separating device is known from <CIT>.

In the foregoing oil separator, the lower chamber is coupled to the tubular base, and therefore is not versatile. That is, the lower chamber is needed to be prepared for each engine to which an oil separator is to be mounted. In addition, a supply passage for oil is restricted because oil is supplied through the fixing member disposed inside the tubular base. This also worsens the versatility of the oil separator. In addition, it is difficult to mount the oil separator to a target object other than an engine, for example, a vehicle body.

The present invention has been made under these circumstances, and an object of the present invention is to provide a highly versatile oil separator which is easy to mount to various targets.

To achieve the above-described object, the present invention is an oil separator for separating mist oil contained in target gas as defined in claim <NUM>.

According to the present invention, the gas introducing portion introducing the target gas from outside and the oil discharge portion discharging the oil to outside are disposed of a joint. In addition, the joint is removably mounted to the housing. Accordingly, it is possible to easily mount the oil separator to various target by preparing an appropriate type of the joint for each target object.

In the above-described oil separator, it is preferable that the joint member includes a common chamber communicating with each of the oil communicating portion, the gas communicating portion, the gas introducing portion, and the oil discharge portion and that the oil communicating portion and the gas communicating portion communicate an upper portion of the common chamber, and that the gas introducing portion communicates a side portion of the common chamber, and that the oil discharge portion communicates a lower portion of the common chamber. In such a configuration, in the common chamber, the target gas introduced the gas introducing portion come into contact with the oil which is flowing down from the oil communicating portion. Accordingly, oil mist contained in the target gas is partially taken into the oil, and this can increase the removal efficiency of oil in the target gas.

In the above-described oil separator, it is preferable that the oil communicating portion is composed of a through-opening formed on a bottom of the housing and penetrating the bottom in a thickness direction and that the gas communicating portion is composed of a tubular portion projecting upward from the bottom of the housing. In such a configuration, the tubular portion constituting the gas communicating portion defines a passage for the target gas. Accordingly, even if oil accumulates at the bottom of the housing, the gas communicating portion ensures a passage for the target gas. Consequently, a large amount of flowing target gas pushes back oil upward, and this can prevent a failure of deterioration of the removal efficiency of oil in blow-by gas.

In the above-described oil separator, it is preferable that an opening of a gas outlet of the gas communicating portion is located on an inner peripheral side with respect to a path of the injection hole. In such a configuration, it is possible to efficiently introduce the target gas.

In the above-described oil separator, it is preferable that the oil separator further comprises a bracket, and that the bracket is mounted to the housing and serves as a section on which the oil separator is mounted to a supporting body. In such a configuration, it is possible to mount the oil separator to a target object other than an engine. For example, the oil separator can be mounted to a vehicle body. In addition, since the mounting position of the bracket to be close to the center of gravity of each rotator (a separation disk, a nozzle, and a spindle), vibration and wobble of the oil separator can be prevented.

According to the present invention, in an oil separator that separates mist oil contained in target gas from the gas, it is possible to easily mount the oil separator to various targets and to increase its versatility.

The following describes embodiments of the present invention with reference to the drawings. The following describes with an example of a closed crankcase ventilation system <NUM> (hereinafter referred to as a ventilation system <NUM>) illustrated in <FIG>.

As illustrated in <FIG>, the ventilation system <NUM> includes an oil separator <NUM> and a breather pipe <NUM>. The oil separator <NUM> processes blow-by gas (equivalent to target gas containing mist oil) discharged from an engine <NUM> to separate the mist oil. In this embodiment, the oil separator <NUM> is mounted at a side surface of an engine <NUM>, which is a target object. The breather pipe <NUM> constitutes a return flow passage, through which the processed blow-by gas discharged from the oil separator <NUM> returns to an intake-side flow passage <NUM> of the engine <NUM>.

In this ventilation system <NUM>, the blow-by gas discharged from the engine <NUM> is introduced to the oil separator <NUM> through a gas introduction pipe 6a. The oil separated by the oil separator <NUM> is returned to the engine <NUM> through an oil discharge pipe 6b. On the other hand, the processed blow-by gas is discharged from an upper end portion of the oil separator <NUM> and then is returned to the intake-side flow passage <NUM> through the breather pipe <NUM>. Specifically, the processed blow-by gas is returned to a part at which an air filter <NUM> is coupled to a turbocharger <NUM> in the intake-side flow passage <NUM>. The returned blow-by gas is mixed with fresh air from the air filter <NUM> and is compressed by the turbocharger <NUM>. Afterwards, the blow-by gas is cooled by a charge cooler <NUM> and is supplied to the engine <NUM>.

The following describes the oil separator <NUM>. As illustrated in <FIG> and <FIG>, this oil separator <NUM> includes a housing <NUM>, which includes a lower case <NUM> and an upper case <NUM>. The housing <NUM> houses various components such as a rotor unit <NUM> and a PCV valve <NUM> in an internal space (a chamber) (described later).

The lower case <NUM> is a part that partitions a lower side part of the housing <NUM>. The lower case <NUM> is constituted of a saucershaped member having a bottom and an opened top surface. The side portion of the lower case <NUM> has a cylindrical shape and a fitted portion is disposed at the upper end portion thereof. This fitted portion is fitted to a lower end portion of the upper case <NUM>. A joint member <NUM> is removably mounted to the lower surface of the lower case <NUM>. In this embodiment, the lower case <NUM>, the communication tube portion, and the like are manufactured by casting; however, the lower case <NUM>, the joint member <NUM>, and the like may be manufactured by molding a resin.

The upper case <NUM> is a member mounted to the lower case <NUM> from above. The upper case <NUM> and the lower case <NUM> separate a chamber that houses components such as the rotor unit <NUM>. An O-ring <NUM> is mounted to a coupling part at which the upper case <NUM> is coupled to the lower case <NUM> (see <FIG>), and this ensures air tightness and liquid tightness. The upper case <NUM> includes a cylindrical body cover <NUM> and a disk-shaped top surface cover <NUM>.

The top surface cover <NUM> is mounted in an airtight manner to the upper end portion of the body cover <NUM>. A tubular gas discharge portion <NUM> is oriented upward at a center of the top surface cover <NUM>. This gas discharge portion <NUM> is a part from which the processed blow-by gas is discharged. The breather pipe <NUM> is coupled to the gas discharge portion <NUM> via an outlet pipe <NUM>.

The following describes an internal structure of the oil separator <NUM>. As illustrated in the exploded perspective view of <FIG>, a chamber formed by the lower case <NUM> and the upper case <NUM> accommodates the rotor unit <NUM>, a partition member <NUM> and a stationary frame <NUM>. As illustrated in the cross-sectional view in <FIG>, a PCV valve <NUM> is mounted to the inside of the top surface cover <NUM>.

First, the following describes the rotor unit <NUM>. This rotor unit <NUM> is a mechanism to separate the mist oil contained in the blow-by gas. As illustrated in <FIG>, the rotor unit <NUM> includes a rotor <NUM>, a spindle <NUM>, and a spindle shaft <NUM>.

The rotor <NUM> is a part that condenses the mist oil by rotation and separates the mist oil from the blow-by gas. The rotor <NUM> includes a plurality of separation disks <NUM>, an upper holder <NUM>, and a lower holder <NUM>. The separation disks <NUM> are ring-shaped plates that incline downward toward the outer peripheral side, in other words, plates having a side surface of a truncated cone shape. The separation disk <NUM> of this embodiment has a thickness of <NUM> or less, and is manufactured by molding resin. These separation disks <NUM> are laminated in an axial direction of the spindle <NUM>. For convenience of explanation, the separation disks <NUM> are illustrated providing intervals from one another; however, the actual intervals are defined to be extremely narrow (for example, less than <NUM>).

The upper holder <NUM> is a member that holds the plurality of laminated separation disks <NUM> from above. Similarly, the lower holder <NUM> is a member that holds the separation disks <NUM> from below. In the outer peripheral edge of the lower holder <NUM>, a plurality of coupling arms 30a for coupling to the upper holder <NUM> are disposed (see <FIG>). In this embodiment, the four coupling arms 30a are provided circumferentially at intervals of <NUM> degrees. The upper ends of the coupling arms 30a are joined to the upper holder <NUM> so that the plurality of separation disks <NUM>, the upper holder <NUM>, and the lower holder <NUM> are integrated to constitute the rotor <NUM>.

This rotor <NUM> has a cylindrical appearance. On the inner peripheral side of the rotor <NUM>, there is a hollow part, and the hollow part vertically extends through. The spindle <NUM> is inserted into this hollow part and the spindle <NUM> and the rotor <NUM> are joined to one another. Accordingly, the rotor <NUM> rotates, together with the spindle <NUM>, around the axis of the spindle <NUM>.

Nozzles <NUM> project from a part of a peripheral surface of the spindle <NUM> located below the rotor <NUM>. Each of the nozzles <NUM> is a part from which the oil supplied through the spindle shaft <NUM> is injected to generate a driving power to rotate the spindle <NUM> and the rotor <NUM>.

The nozzles <NUM> of this embodiment include cylindrical nozzle bodies <NUM> and injection holes <NUM> disposed at distal end portions of the nozzle bodies <NUM>. Base ends of the nozzle bodies <NUM> are coupled to the spindle <NUM>, and the distal ends of the nozzle bodies <NUM> are closed. The nozzle bodies <NUM> are mounted at an angle of <NUM> degrees obliquely downward with respect to the axial direction of the spindle <NUM>. The three nozzle bodies <NUM> are circumferentially disposed at intervals of <NUM> degrees. The injection hole <NUM> is disposed on a side surface at the distal end portion of the nozzle body <NUM>. More specifically, the injection hole <NUM> is disposed in a direction perpendicular to the axial direction of the nozzle body <NUM> so that oil is injected horizontally.

The spindle shaft <NUM> is a pillar member serving as a bearing of the spindle <NUM>, and supports the spindle <NUM> in a rotatable manner. The spindle shaft <NUM> internally includes an oil supply passage 27a to supply the oil. A lower end portion of the spindle shaft <NUM> is coupled to an upper end portion of a support tube portion <NUM> disposed in the lower case <NUM>. The support tube portion <NUM> corresponds to the oil supply portion, and supplies the oil supply passage 27a with oil which has injected from the injection holes <NUM>. And, the oil supply pipe 6c illustrated in <FIG> is coupled to the support tube portion <NUM>. Accordingly, the oil supplied through the oil supply pipe 6c passes through the support tube portion <NUM>, and then flows into the spindle shaft <NUM>. Thereafter, the oil flows into the nozzle bodies <NUM>, and then is injected from the injection holes <NUM>.

As described above, the injection hole <NUM> is disposed at the distal end portion of the nozzle body <NUM> in a direction in which oil is injected horizontally. At the three nozzles <NUM> disposed at intervals of <NUM> degrees, formation positions for the injection holes <NUM> are matched. Accordingly, when the oil is injected from the respective injection holes <NUM>, the rotor <NUM> and the spindle <NUM> rotate about the spindle shaft <NUM> as the axis.

The following describes the partition member <NUM>. As illustrated in <FIG>, the partition member <NUM> is a member that partitions the internal space (the chamber) of the housing <NUM> into a lower chamber <NUM> (a primary separation chamber) and an upper chamber <NUM> (a secondary separation chamber). And the partition member <NUM> forms a communication port <NUM>. The blow-by gas in the lower chamber <NUM> is guided by the communication port <NUM> to the upper chamber <NUM>. The partition member <NUM> has an outer peripheral portion <NUM> and a tapered portion <NUM>. The outer peripheral portion <NUM> is a short cylindrical part and has a collar portion <NUM> projecting outwardly at the middle in the height direction. The tapered portion <NUM> is disposed on the inner peripheral side with respect to the outer peripheral portion <NUM>, and has a tapered shape in which the diameter is gradually reduced from the lower end of the outer peripheral portion <NUM> toward the top. The tapered portion <NUM> of this embodiment has an inclined surface that inclines downward toward an outer peripheral side. an upper end opening of the tapered portion <NUM> forms the communication port <NUM>.

The partition member <NUM> is fitted to the inner peripheral side of the fitted portion in the lower case <NUM>. The collar portion <NUM> abuts on an upper end of the fitted portion from above to be positioned. Consequently, the tapered portion <NUM> is disposed immediately below the lower holder <NUM> included in the rotor <NUM>. The chamber is partitioned into the lower chamber <NUM> and the upper chamber <NUM>, which are bordered by the partition member <NUM>. These lower chamber <NUM> and upper chamber <NUM> are communicated through the communication port <NUM>.

When the rotor <NUM> rotates at a high speed, oil film, which is turning at high speed, is formed on the outer peripheral side with respect to the turning paths of the injection holes <NUM>. When the blow-by gas contacts this oil film, the mist oil contained in the blow-by gas is taken in the oil film and is centrifuged. This makes it possible to reduce the mist oil content in the blow-by gas. Thus, in the lower chamber <NUM>, the mist oil content in the blow-by gas can be reduced by the injection of the oil, which functions as the driving source for the spindle <NUM> and the rotor <NUM>. Therefore, the lower chamber <NUM> functions as the primary separation chamber for the mist oil.

The following describes the PCV valve <NUM>. As illustrated in <FIG>, the PCV valve <NUM> includes a diaphragm <NUM>, upper springs <NUM>, and lower springs <NUM>.

The diaphragm <NUM> is a valve element and is manufactured by molding rubber and resin. The diaphragm <NUM> is composed of a disk-shaped member. The upper springs <NUM> and the lower springs <NUM> are members to support the diaphragm <NUM> in such a manner that the diaphragm <NUM> can move vertically. The PCV valve <NUM> is placed on a pedestal portion at a position immediately below the top surface cover <NUM>. The diaphragm <NUM> covers this pedestal portion in an airtight manner. a space defined by the pedestal portion and the diaphragm <NUM> is open to open air through an air communicating portion.

The diaphragm <NUM> vertically moves according to intake-side pressure of the engine <NUM> and internal pressure of the crankcase, to adjust the flow of the blow-by gas. That is, under an excessively large intake pressure (negative pressure) of the engine <NUM>, the diaphragm <NUM> moves toward the gas discharge portion <NUM> (upward), and under a high pressure of the side close to the crankcase, the diaphragm <NUM> moves toward the opposite side (downward).

Accordingly, when the pressure in the upper chamber <NUM> becomes higher than a PCV-set pressure, the diaphragm <NUM> moves downward to increase a flow rate of the blow-by gas. On the contrary, when the pressure in the upper chamber <NUM> is lower than the PCV-set pressure, the diaphragm <NUM> moves upward to reduce the flow rate of the blow-by gas. Thus, the flow rate of the blow-by gas is appropriately adjusted, and thereby the crankcase-side pressure of the engine <NUM> maintains within a constant range.

An outer periphery of the pedestal portion on which the PCV valve <NUM> is placed is defined by a sidewall portion, the sidewall portion having a circular shape as viewed from above. a communicating window <NUM> is disposed at this sidewall portion. Through this communicating window <NUM>, an upper part of the upper chamber <NUM> with respect to the diaphragm <NUM> and a part of the upper chamber <NUM> on the rotor <NUM> side communicate.

A cylindrical rib <NUM> is disposed at the lower side of the sidewall portion. This cylindrical rib <NUM> is a ring-shaped projection disposed at a position higher than the rotor unit <NUM> and lower than the diaphragm <NUM>, and the cylindrical rib <NUM> is integrated with the body cover <NUM>. In the upper end part of the body cover <NUM>, the cylindrical rib <NUM> guides downwards fluid (oil and blow-by gas) which is flowing along the inner surface of the body cover <NUM> from the outer peripheral side to the inner peripheral side. Since this cylindrical rib <NUM> can also reduce the amount of oil, it is possible to surely restrain an attachment of the oil to the PCV valve <NUM>.

The lower case <NUM> and the joint member <NUM> will be described below. As illustrated in <FIG>, the lower case <NUM> has a disk-shaped bottom <NUM>. A cylindrical-shaped side portion <NUM> is disposed upright from an outer peripheral edge of the bottom <NUM>. On the center of the bottom <NUM>, an outlet-side part of the support tube portion <NUM>, which is the side on which oil is discharged, is disposed upright. As illustrated in <FIG>, an upper end of the support tube portion <NUM>, which is a flow-in side to the oil supply passage 27a, is fitted to the stationary frame <NUM>. This stationary frame <NUM> is a metallic frame (see <FIG>) disposed to increase the rigidity of the support tube portion <NUM>. As illustrated in <FIG>, the inlet-side part of the support tube portion <NUM>, which is the flow-in side of oil, extends along the bottom <NUM> toward the side. In addition, an end portion of the inlet-side part is open to outside at the side surface of the lower case <NUM>.

In addition, a gas communicating portion <NUM> is disposed along the outlet-side part of the support tube portion <NUM>. This gas communicating portion <NUM> introduces the blow-by gas from the inside of the joint member <NUM> to the inside of the lower case <NUM>. The gas communicating portion <NUM> according to the present invention is a cylinder portion that penetrates the bottom <NUM> of the lower case <NUM> and that projects upward. An upper end (a gas outlet) of the gas communicating portion <NUM> is positioned on the inner peripheral side with respect to the paths of the injection holes <NUM> provided with the nozzles <NUM>. Oil communicating portions <NUM> for discharging oil are disposed at the bottom <NUM> of the lower case <NUM>. These oil communicating portions <NUM> are openings that penetrate the bottom <NUM> of the lower case <NUM> in the thickness direction. In the present invention, the oil communicating portions <NUM> are disposed at positions that surround the support tube portion <NUM> and the gas communicating portion <NUM>.

The joint member <NUM> is a member mounted to the bottom <NUM> of the lower case <NUM> from the lower side. The joint member <NUM> includes a joint body <NUM>, a mounting flange <NUM>, a gas introducing portion <NUM>, and an oil discharge portion <NUM>.

The joint body <NUM> is a rectangular parallelepiped hollow member whose top surface is open. The internal space of the joint body <NUM> serves as a common chamber. The mounting flange <NUM> is a part used to mount the joint member <NUM> to the lower case <NUM>. The mounting flange <NUM> is composed of plates which projects laterally from an upper end of the joint body <NUM>. The mounting flange <NUM> includes screw openings provided respectively in its four corners. A fixing male screw is inserted into each screw opening, and is tightened into a female screw part formed on the bottom <NUM> of the lower case <NUM>. Thereby, the joint member <NUM> is mounted to the lower case <NUM>. Between the joint member <NUM> and the lower case <NUM>, a rectangular ring-shaped packing <NUM> is mounted to ensure liquid tightness.

The gas introducing portion <NUM> is a part that introduces the blow-by gas to the inside of the oil separator <NUM>, the blow-by gas being flowing in through the gas introduction pipe 6a. The gas introducing portion <NUM> is a cylindrical member laterally projecting from a sidewall of the joint body <NUM>. The gas introducing portion <NUM> communicates an internal space 55a (the common chamber) of the joint body <NUM> on the side of the joint body <NUM>. An end portion of the gas introduction pipe 6a is coupled to the projection part of the gas introducing portion <NUM>.

The oil discharge portion <NUM> is a part for discharging to the engine <NUM> the oil which flows down from the oil communicating portions <NUM> of the lower case <NUM>. The oil discharge portion <NUM> is a cylindrical member projecting downward from the bottom <NUM> of the joint body <NUM>. The oil discharge portion <NUM> communicates the internal space 55a of the joint body <NUM> on the lower side of the joint body <NUM>. To the projection part of the oil discharge portion <NUM>, an end portion of the oil discharge pipe 6b is coupled.

<FIG> is a drawing of the lower case <NUM>, to which the joint member <NUM> is mounted, as viewed in a planar direction. As illustrated in <FIG>, when the joint member <NUM> is mounted to the lower case <NUM>, the oil discharge portion <NUM> is positioned immediately below the oil communicating portions <NUM>. Accordingly, the oil flowing down from the oil communicating portions <NUM> is smoothly discharged from the oil discharge portion <NUM>.

Here, the separation of the mist oil from the blow-by gas in the oil separator <NUM> having the foregoing configuration will be described.

As illustrated in <FIG>, the oil which has been supplied to the support tube portion <NUM> flows into the spindle shaft <NUM> as indicated by a path of reference symbol F1. The oil flows from the spindle shaft <NUM> to the nozzle bodies <NUM> and is injected from the injection holes <NUM>. By the injection of the oil from each injection hole <NUM>, the rotor <NUM> and the spindle <NUM> rotate around the spindle shaft <NUM>.

The oil which has been injected from the injection holes <NUM> moves along the path indicated by reference symbol F2. That is, the injected oil is sprayed to the tapered portion <NUM> of the partition member <NUM>. And then, the oil is guided obliquely below toward the outer peripheral side along the inclined surface of the tapered portion <NUM>. Accordingly, a mixture of oil spray to the blow-by gas is restrained. Afterwards, the oil flows down on the inner surface of the lower case <NUM>, and flows into the internal space 55a of joint member <NUM> from the oil communicating portion <NUM>. And, the oil flows into the oil discharge portion <NUM> and is returned to the engine <NUM> through the oil discharge pipe 6b.

On the other hand, blow-by gas introduced from the engine <NUM> through the gas introduction pipe 6a moves along the path indicated by the arrow of reference symbol F3. That is, the blow-by gas flows into the gas introducing portion <NUM> of the joint member <NUM>. The blow-by gas which has passed the gas introducing portion <NUM> flows into the gas communicating portion <NUM> from the internal space 55a of the joint body <NUM>. The blow-by gas which has passed the gas communicating portion <NUM> flows into the hollow part of the rotor <NUM> through an area inside the motion paths of the injection holes <NUM>.

The blow-by gas flowing into the hollow part of the rotor <NUM> moves through the clearances between the separation disks <NUM> to the outer peripheral direction of the rotor <NUM> due to a centrifugal force which is generated by the rotation of the rotor <NUM>. Thus, when the blow-by gas moves to the outer peripheral direction of the rotor <NUM> due to the centrifugal force, the pressure at the inner peripheral side of the rotor <NUM> becomes lower than the pressure at the outer peripheral side. Due to the pressure difference, the blow-by gas which has passed the gas communicating portion <NUM> becomes more likely to flow into the hollow part at the rotor <NUM>, and thereby the flow efficiency of the blow-by gas increases.

When the blow-by gas comes into contact with the separation disks <NUM>, the mist oil contained in this blow-by gas attaches to the surfaces of the separation disks <NUM>. The attached mist oil and additional mist oil coalesce, and thus the oil condenses on the surfaces of the separation disks <NUM>. That is, the oil undergoes secondary separation. As described above, in the lower chamber <NUM>, the mist oil is separated from the blow-by gas by primary separation. Accordingly, by the secondary separation at the separation disks <NUM>, the mist oil is separated from the blow-by gas at a high level. Thus, the upper chamber <NUM> corresponds to the secondary separation chamber in which the secondary separation of the remaining mist oil is performed to separate the remaining mist oil from the blow-by gas which has undergone primary separation of the mist oil.

As shown in <FIG>, a clearance SP is formed between the spindle <NUM> and the spindle shaft <NUM>. This clearance SP serves as an oil guiding passage and is filled with the oil which is supplied to be injected from the nozzles <NUM>. Since the oil supply pressure is sufficiently high, some oil filling the clearance passes through the upper end of the clearance and is discharged from the upper end portion of the spindle <NUM> to the hollow part of the rotor <NUM>. Similar to the blow-by gas, due to the centrifugal force of the rotor <NUM>, the oil discharged to the hollow part of the rotor <NUM> moves through the clearances between the separation disks <NUM> to the outer peripheral direction of the rotor <NUM>.

The oil condensed on the surfaces of the separation disks <NUM> coalesces with the oil discharged to the hollow part of the rotor <NUM>. This cleans the surfaces of the separation disks <NUM>, and therefore simplifies maintenance for the separation disks <NUM>.

The oil which has been condensed on the surfaces of the separation disks <NUM> and the oil which has coalesced move along the path indicated by reference symbol F4 in <FIG>. That is, the oil is discharged from the outer peripheral edges of the separation disks <NUM>, and collides with the inner surface of the body cover <NUM>, and then flows down along this inner surface. And, the oil joins the oil injected from the nozzles <NUM> in the lower case <NUM>, and passes the oil communicating portion <NUM>, the oil discharge portion <NUM>, and the oil discharge pipe 6b. Finally, the oil is returned to the engine <NUM>.

The blow-by gas that has passed through the rotor <NUM> and from which the mist oil has been separated moves along a path indicated by reference symbol F5 in <FIG>. That is, the blow-by gas that has passed through the rotor <NUM> becomes a turning flow and moves up inside the upper case <NUM>. Thus, the blow-by gas is introduced to a top-surface-side space of the PCV valve <NUM>. Afterwards, the blow-by gas moves through the outlet pipe <NUM> and is introduced to the breather pipe <NUM>.

In the oil separator <NUM> according to the present embodiment which operates as described above, the oil communicating portions <NUM> and the gas communicating portion <NUM> communicate the upper portion of the internal space 55a (the common chamber) of the joint body <NUM>. The gas introducing portion <NUM> communicates the internal space 55a of the joint body <NUM> on the side of the joint body <NUM>. The oil discharge portion <NUM> communicates the internal space 55a of the joint body <NUM> on the lower side of the joint body <NUM>. Accordingly, in the internal space 55a of the joint body <NUM>, the blow-by gas introduced from the gas introducing portion <NUM> come into contact with the oil which is flowing down from the oil communicating portions <NUM>. Thus, oil mist contained in the blow-by gas is partially taken into the oil, and this can increase the removal efficiency of oil in the blow-by gas.

The oil communicating portions <NUM> are composed of throughopenings, which are formed on the bottom <NUM> of the lower case <NUM> and which penetrate through the bottom <NUM> in the thickness direction. The gas communicating portion <NUM> is composed of a tubular portion projecting upward from the bottom <NUM> of the lower case <NUM>. That is, the tubular portion constituting the gas communicating portion <NUM> defines a passage for blow-by gas extending vertically. Accordingly, a large amount of oil flows in through a path indicated by reference symbol F6 in <FIG>. Even if the oil accumulates at the bottom <NUM> of the lower case <NUM>, the gas communicating portion <NUM> ensures a passage for blow-by gas, as indicated by reference symbol F7. Consequently, a large amount of flowing blow-by gas pushes back the oil upward, and this can prevent a failure of deterioration of the removal efficiency of oil in the blow-by gas. Additionally, the gas outlet of the gas communicating portion <NUM> is disposed on the inner peripheral side with respect to the paths of the injection holes <NUM>. This makes it possible to efficiently introduce the blow-by gas to the hollow part of the rotor <NUM>.

Here, a bracket <NUM> for mounting the oil separator <NUM> to the engine <NUM> will be described. The bracket <NUM> illustrated in <FIG> includes a mounting base 61a and forks 61b. The mounting base 61a is a part mounted to the engine <NUM> and is composed of a trapezoidalshaped metal plate. The forks 61b are two elongated plate-shaped portions extending from both lower ends of the mounting base 61a in a direction perpendicular to the mounting base 61a. A plurality of screw holes are disposed in each of the mounting base 61a and forks 61b. Fixing screws are inserted into the screw holes and are tightened. Thereby, the mounting base 61a is mounted to a side surface of the engine <NUM>, and the forks 61b is fixed to the bottom surface of the lower case <NUM>.

The use of this bracket <NUM> allows a mounting position of the bracket <NUM> to be close to the center of gravity of each rotator (the separation disks <NUM>, the nozzles <NUM>, and the spindle <NUM>). This can prevent vibration and wobble of the oil separator <NUM>. In addition, this also makes it possible to mount the oil separator <NUM> to a target object other than the engine <NUM>. For example, the oil separator <NUM> can be mounted to a vehicle body.

The following describes variations of the joint member <NUM>. First, the first modification illustrated in <FIG> differs from the above-described embodiment in that the gas introducing portion <NUM> provided with the joint member <NUM> is composed of an elbow member. In the first modification, the gas introducing portion <NUM> is composed of the elbow member being capable of nodding. Therefore, even if the position of the gas introduction pipe 6a, which introduces the blow-by gas, is restricted, this restriction can be dealt with relatively easily.

The second modification illustrated in <FIG> differs from the above-described embodiment in that the gas introducing portion <NUM> and the oil discharge portion <NUM> include flanges 57a and 58a. In the second modification, the flanges 57a and the flange 58a are respectively disposed of the gas introducing portion <NUM> and the oil discharge portion <NUM>. This makes it possible to couple easy to the gas introduction pipe 6a and the oil discharge pipe 6b, which include these flanges.

The third modification illustrated in <FIG> differs from the above-described embodiment in that the third modification uses a joint member 14A where the gas introducing portion <NUM> and the oil discharge portion <NUM> are integrated.

As apparent from the above-described embodiment and these first modification to third modification, in this oil separator <NUM>, the gas introducing portion <NUM> and the oil discharge portion <NUM> are disposed of the joint, and this joint is removably mounted to the lower case <NUM>. Accordingly, it is sufficient to prepare the joint member <NUM> or 14A according to a vehicle type to which the oil separator <NUM> is to be mounted. This makes it possible to easily mount the oil separator <NUM> to various targets. Other components can be shared, and mass production of the oil separator can be achieved, which results in cost reduction.

Claim 1:
An oil separator for separating mist oil contained in target gas, the oil separator comprising:
a rotor (<NUM>) that is rotatable together with a spindle (<NUM>) and separates the mist oil by rotation;
wherein the oil separator further comprises:
a nozzle (<NUM>) that is projected from a part of a peripheral surface of the spindle, the part being located below the rotor, and that injects oil from an injection hole (<NUM>) to rotate the spindle around an axis;
a housing (<NUM>) including:
an oil supply portion (<NUM>) that supplies oil to be injected from the injection hole;
oil communicating portions (<NUM>) for discharging oil injected from the injection hole; and
a gas communicating portion (<NUM>) for introducing the target gas;
wherein the oil communicating portions (<NUM>) are disposed at positions that surround a support tube portion (<NUM>) and the gas communicating portion (<NUM>); and
a joint member (<NUM>) that is removably mounted to the housing and includes a gas introducing portion (<NUM>) and an oil discharge portion (<NUM>), the gas introducing portion introducing the target gas from outside and transferring the target gas to the gas communicating portion, the oil discharge portion receiving oil from the oil communicating portion and discharging the oil to outside.