EGR gas distributor

The EGR gas distributor is attached to an intake manifold to distribute EGR gas to each of branch pipes constituting the intake manifold. The EGR gas distributor includes a gas distribution part including a gas inlet port for EGR gas, a plurality of gas outlet ports connected to each corresponding branch pipe, and a gas passage that extends by branching off into a plurality of branch sections from the gas inlet port to each gas outlet port. The gas passage has a tournament branch shape that extends by stepwise branching off from the gas inlet port to each gas outlet port and is symmetric about the gas inlet port. The EGR gas distributor includes a heating part provided adjacent to the entire gas distribution part to heat the gas distribution part. The heating part is constituted of a hot-water passage part configured to allow hot water to flow therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2017-234140 filed on Dec. 6, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to an EGR (Exhaust Gas Recirculation) gas distributor to be attached to an intake manifold in use to distribute EGR gas to a plurality of cylinders of an engine.

Related Art

As the above type of technique, conventionally, there has been known for example a gas distribution part of an intake manifold disclosed in Japanese unexamined patent application publication No. 2006-241992 (JP2006-241992A). This intake manifold will be mounted together with an engine in a vehicle and is provided with a surge tank and a plurality of intake pipes (branch pipes) branched from the surge tank in one-to-one correspondence to cylinders of the engine. The gas distribution part is configured to distribute auxiliary gas, such as EGR gas and PCV gas, to each of the branch pipes. This gas distribution part includes a gas inlet port connected to a single gas supply source, gas outlet ports that open into each of the branch pipes, and a gas passage that extends by branching off into a plurality of branch sections from the gas inlet port to each gas outlet port. The gas passage is designed such that the pressure loss in each branch section from the gas inlet port to each gas outlet port is equal between the branch sections. The gas passage has a tournament branch shape that extends by stepwise branching from the gas inlet port to each gas outlet port and is symmetric about the gas inlet port. According to this configuration, in which the gas passage takes the tournament branch shape, the EGR gas distributor can appropriately distribute EGR gas to each of the branch pipes.

SUMMARY

Technical Problem

However, when EGR gas is adopted as the auxiliary gas, for example, the technique disclosed in JP2006-241992A may cause condensed water to be generated from water or moisture contained in the EGR gas in the gas passage during cold start or others of the engine. If this condensed water flows in a branch pipe(s) through the corresponding gas outlet port(s), it may be sucked into the cylinder(s), thus causing misfire in the engine. To avoid such a defect, it is usually arranged to delay introduction of EGR gas into the intake manifold until the gas passage is warmed to a certain degree. However, this delay of introduction of EGR gas into the intake manifold makes it impossible to introduce EGR gas into the engine by just that much, so that fuel economy of the engine could not be improved. Herein, in order to prevent the delay of EGR gas introduction into the engine, it is necessary to quickly warm the gas passage to thereby suppress the generation of condensed water.

The present disclosure has been made to address the above problems and has a purpose to provide an EGR gas distributor capable of effectively quickly warm a gas passage while enhancing the performance of distributing EGR gas.

Means of Solving the Problem

To achieve the above-mentioned purpose, one aspect of the present disclosure provides an EGR gas distributor that is an attachment device to be attached to an intake manifold and is configured to distribute EGR gas to each of a plurality of branch pipes constituting the intake manifold, the EGR gas distributor comprising: a gas distribution part including: a single gas inlet port configured to allow EGR gas to flow in the gas distribution part; a plurality of gas outlet ports connected to each of the branch pipes; and a gas passage configured to extend by branching off into a plurality of branch sections from the gas inlet port to each of the gas outlet ports, the gas passage having a tournament branch shape that extends by stepwise branching off from the gas inlet port to each of the gas outlet ports and is symmetric about the gas inlet port; and a heating part provided adjacent to the entire gas distribution part to heat the gas distribution part.

According to the present disclosure, the above configuration can effectively quickly warm the gas passage while enhancing the performance of distributing EGR gas.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

First Embodiment

A detailed description of an embodiment of an EGR gas distributor of this disclosure will now be given referring to the accompanying drawings.

(Relationship Between EGR Gas Distributor and Intake Manifold)

FIG. 1is a perspective view of an EGR gas distributor1attached to an intake manifold2.FIG. 2is a perspective view of the EGR gas distributor1and the intake manifold2shown inFIG. 1, taken along a vertical plane passing through a line A-A perpendicular to a longitudinal direction of the EGR gas distributor1at a position of a gas outlet port23A.FIG. 3is a perspective view of the EGR gas distributor1and the intake manifold2shown inFIG. 1, taken along a vertical plane passing through a line B-B perpendicular to the longitudinal direction of the EGR gas distributor at a position of a gas inlet port19.FIG. 4is a cross-sectional view showing a cut plane of the EGR gas distributor1and the intake manifold2inFIG. 2.FIG. 5is a cross-sectional view showing a cut plane of the EGR gas distributor1and the intake manifold2inFIG. 3.

The posture of the EGR gas distributor1shown inFIG. 1represents a configuration state of the EGR gas distributor1when attached to the intake manifold2mounted in an engine. The orientation of the EGR gas distributor1in the engine in vertical and lateral directions is defined as shown inFIG. 1. The intake manifold2is provided, as is known, with a surge tank3, a plurality of branch pipes4A,4B,4C, and4D each branched from the surge tank3, and an outlet flange5connecting each of the branch pipes4A to4D to the engine. In the present embodiment, the intake manifold2includes four branch pipes4A to4D corresponding to a 4-cylinder engine and is made of resin. The EGR gas distributor1is an attachment device to be attached to the intake manifold2in use to distribute EGR gas to each of the branch pipes4A to4D of the intake manifold2.

(Outline of EGR Gas Distributor)

FIG. 6is a perspective view of the EGR gas distributor1seen from the front side.FIG. 7is a perspective view of the EGR gas distributor1inFIG. 6, from which a cover member12is removed.FIG. 8is a perspective view of the EGR gas distributor1seen from the back side.FIG. 9is a plan view of the EGR gas distributor1.FIG. 10is a plan view of the EGR gas distributor1inFIG. 9, from which the cover member12is removed.FIG. 11is a right side view of the EGR gas distributor1.FIG. 12is a cross-sectional view of the EGR gas distributor1taken along a line C-C inFIG. 9.FIG. 13is a cross-sectional view of the EGR gas distributor1taken along a line D-D inFIG. 11.

As shown inFIGS. 6 to 10, the EGR gas distributor1entirely has a long thin box-shaped appearance and includes a body casing11, the cover member12fixed to an upper surface, which is one side surface, of the body casing11, a hot-water inflow casing13fixed to a left side surface of the body casing11, and a hot-water outflow casing14fixed to a right side surface of the body casing11. The body casing11has a long shape, concretely, a substantially rectangular shape in planar view and includes a gas distribution part15(seeFIG. 12) to distribute EGR gas, a heating part16to heat the gas distribution part15, and a partition wall17(seeFIG. 12) that separates between the gas distribution part15and the heating part16. The body casing11extends in a direction traversing the branch pipes4A to4D. In the present embodiment, the heating part16is constituted of a hot-water passage part18(seeFIG. 12and other figures) configured to allow hot water to flow therethrough. The body casing11includes a gas inlet port19(seeFIG. 8and other figures) formed at the center of the rear side of the body casing11and a plurality of gas outlet pipes20A,20B,20C, and20D each protruding from the front side of the body casing11. The hot-water inflow casing13has a substantially triangular shape in planar view with a distal end in which a pipe joint21is provided extending outward therefrom. Similarly, the hot-water outflow casing14has a substantially triangular shape in planar view with a distal end in which a pipe joint22is provided extending outward therefrom. The hot-water inflow casing13and the hot-water outflow casing14are fixed to the body casing11with bolts10to close openings of the body casing11at both ends in the longitudinal direction. The gas inlet port19and each gas outlet pipe20A to20D are included in the gas distribution part15. The hot-water inflow casing13, hot-water outflow casing14, and pipe joints21and22are included in the hot-water passage part18. The body casing11, cover member12, hot-water inflow casing13, and hot-water outflow casing14can be made of resin. In particular, the body casing11and the cover member12can be made of a resin material having good thermal conductivity. For example, the resin material having good thermal conductivity can be a resin material mixed with carbon powder.

The gas distribution part15includes, as shown inFIGS. 4 to 10, the single gas inlet port19configured to allow EGR gas to flow in the gas distribution part15, a plurality of gas outlet ports23A,23B,23C, and23D respectively connected to the branch pipes4A,4B,4C, and4D through the gas outlet pipes20A,20B,20C, and20D, and a gas passage24configured to extend by branching off into a plurality of branch sections from the gas inlet port19to the gas outlet ports23A to23D. In the gas outlet ports23A to23D, the corresponding gas outlet pipes20A to20D are respectively fixedly fitted. In the present embodiment, the gas passage24has a tournament branch shape that extends by stepwise branching off from the gas inlet port19to the gas outlet ports23A to23D and is symmetric about the gas inlet port19, as indicated by broken lines inFIG. 9. In the present embodiment, the partition wall17has an upper surface17b(one side surface) formed with a recess25, in a groove shape, having the tournament branch shape (seeFIG. 12), so that the gas passage24is formed by the recess25in cooperation with the cover member12that covers the recess25. In the present embodiment, the cover member12also has an inner surface12aformed with a recess26(seeFIG. 12) having the tournament branch shape matching the recess25of the body casing11. Those upper recess26and lower recess25cooperatively constitute the gas passage24. In the present embodiment, the gas passage24is designed such that the pressure loss between the gas inlet port19and each of the gas outlet ports23A to23D is equal between the branch passages of the gas passage24. The gas inlet port19can be connected to an EGR passage for supplying EGR gas through an EGR valve.

The hot-water passage part18is provided adjacent to the entire gas distribution part15(the gas passage24) through the partition wall17to heat the gas distribution part15as shown inFIGS. 4, 5, 12, and 13. The hot-water passage part18includes a hot-water passage31configured to allow hot water to flow therethrough, a hot-water inlet port32configured to allow hot water to flow in the hot-water passage31, and a hot-water outlet port33configured to allow hot water to flow out of the hot-water passage31. The hot-water inlet port32is formed in the hot-water inflow casing13. In this inlet port32, the pipe joint21is fixedly fitted. The hot-water outlet port33is formed in the hot-water outflow casing14. In this outlet port33, the pipe joint22is fixedly fitted. Each of the pipe joints21and22is connected to a pipe to allow engine cooling water (hot water) to flow. As shown inFIG. 12, the hot-water inlet port32and the hot-water outlet port33are aligned on one imaginary line, i.e., the same imaginary line L1that is parallel to an axis line L0of the body casing11in a longitudinal direction. In the present embodiment, as shown inFIG. 12, the imaginary line L1is in a position displaced above the axis line L0of the body casing11(i.e., displaced closer to the gas passage24relative to the axis line L0) inFIG. 12.

The hot-water passage31extends in the longitudinal direction of the body casing11, hot-water inflow casing13, and hot-water outflow casing14as shown inFIG. 13. The hot-water passage31includes a first end part E1and a second end part E2, located at both ends in the longitudinal direction, and a middle part M0located between the first end part E1and the second end part E2. In the present embodiment, the first end part E1of the hot-water passage31is constituted of the hot-water inflow casing13, the second end part E2is constituted of the hot-water outflow casing14, and the middle part M0is constituted of the body casing11. The hot-water inflow casing13has the distal end in which the hot-water inlet port32is placed. The first end part E1of the hot-water passage31has a shape widening from the hot-water inlet port32toward the middle part M0. In contrast, the hot-water outflow casing14has the distal end in which the hot-water outlet port33is placed. The second end part E2of the hot-water passage31has a shape widening from the hot-water outlet port33toward the middle part M0.

In the hot-water passage31, the portion of the partition wall17that forms the gas passage24is designed to be thicker than other portions and project into the hot-water passage31as shown inFIG. 12. Herein, for stable transfer of the heat of hot water to the gas passage24, it is necessary to ensure adequate flow velocity of hot water in the hot-water passage31. Therefore, the projected portion of the partition wall17is formed with a convex curved surface17awith a smooth edge in order to minimize the pressure loss of hot water caused by the projected portion.

According to the configuration of the present embodiment described above, the EGR gas distributor1will be attached to the intake manifold2mounted in the engine. While the EGR gas distributor1is in this attachment state, during engine cold state, cooling water (hot water) flows through the hot-water passage part18corresponding to the heating part16. This heating part16is provided adjacent to the entire gas distribution part15, so that the inner wall of the overall gas passage24is quickly warmed by the heat of the heating part16. In the hot-water passage part18, specifically, the hot water introduced into the hot-water passage31through the hot-water inlet port32flows through the hot-water passage31and then flows out through the hot-water outlet port33. Herein, since the hot-water passage part18is placed adjacent to the entire gas distribution part15, the inner wall of the overall gas passage24is quickly warmed by the heat of hot water flowing through the hot-water passage31of the hot-water passage part18. Furthermore, in the gas distribution part15, EGR gas introduced into the gas passage24through the gas inlet port19is distributed to each of the branch pipes4A to4D through each of the corresponding gas outlet ports23A to23D. Herein, the gas passage24extends by stepwise branching from the gas inlet port19to the gas outlet ports23A to23D, thus taking a tournament branch shape symmetric about the gas inlet port19. Accordingly, the EGR gas introduced into the gas passage24through the gas inlet port19is evenly split at each junction toward the gas outlet ports23A to23D in a stepwise manner until the split streams of EGR gas reach the gas outlet ports23A to23D. This configuration can effectively quickly warm the gas passage24while enhancing the performance of distributing EGR gas. In addition, since the heating part16is constituted of the hot-water passage part18, for example, engine cooling water can be utilized as hot water. Thus, the inner wall of the entire gas passage24can be warmed by use of the hot water such as engine cooling water from an early stage during engine cold start without needing an electric structure such as an electric heater or energy. This can suppress the generation of condensed water on the inner wall of the gas passage24, thus enabling start of EGR with respect to an engine from an early stage during cold start.

According to the configuration in the present embodiment, the gas distribution part15, the hot-water passage part18, and the partition wall17can be made integrally in the body casing11. Further, the recess25having the tournament branch shape is formed in one side surface (the upper surface17b) of the partition wall17. This recess25forms the gas passage24in cooperation with the cover member12placed to cover the recess25. Accordingly, the gas passage24can be formed more easily than when a gas passage is formed by only the body casing11. Thus, the EGR gas distributor can be easily designed with a desired configuration without increasing its dimension.

According to this configuration in the present embodiment, the first end part E1of the hot-water passage31(the hot-water inflow casing13) takes the shape widening from the hot-water inlet port32toward the middle part M0(the body casing11), thus allowing the hot water introduced into the hot-water passage31through the hot-water inlet port32to flow so as to spread into the entire area of the hot-water passage31. Further, the second end part E2(the hot-water outflow casing14) of the hot-water passage31forms a shape widening from the hot-water outlet port33toward the middle part M0(the body casing11), thus allowing the hot water flowing through the hot-water passage31to flow to converge on the hot-water outlet port33. Consequently, the hot water is made to smoothly flow through the hot-water passage31. This smooth flow is also enhanced by the placement of the hot-water inlet port32and the hot-water outlet port33aligned on the same imaginary line L1. This makes it possible to ensure the sufficient flow velocity of hot water flowing through the hot-water passage31and hence enhance the performance of heat transmission from the hot-water passage part18(the hot-water passage31) to the gas distribution part15(the gas passage24).

In the present embodiment, the imaginary line L1on which the hot-water inlet port32and the hot-water outlet port33are aligned is located at a position displaced closer to the gas passage24relative to the axis line L0of the body casing11. Thus, the center line of the flow of hot water directed from the hot-water inlet port32toward the hot-water outlet port33is displaced closer to the gas passage24. In this regard, the gas passage24can be effectively warmed by hot water.

Second Embodiment

Next, a second embodiment of the EGR gas distributor will be described below with reference to the attached drawings.

In the following description, identical or similar parts to those in the first embodiment are assigned the same reference signs as in the first embodiment and their details are not repeated. Thus, the following description will be given with a focus on differences from the first embodiment.

The present embodiment differs from the first embodiment in the configuration of the gas passage24.FIG. 14is a cross-sectional view of the EGR gas distributor1in the second embodiment, corresponding toFIG. 12. In the first embodiment described above, both the partition wall17and the cover member12are respectively provided with the recess25and the recess26to cooperatively form the gas passage24. In contrast, in the present embodiment, the partition wall17is provided with no recess, whereas only the cover member12is provided with the recess26as shown inFIG. 14. Specifically, the recess26is formed in a tournament branch shape only in the inner surface12aof the cover member12. Thus, the gas passage24is formed by the recess26of the cover member12placed on the partition wall17so that the inner surface12aof the cover member12overlaps with one side surface (the upper surface17b) of the partition wall17to cover the partition wall17.

According to the configuration of the present embodiment, the gas distribution part15, the hot-water passage part18, and the partition wall17can be made integrally in the body casing11. Further, the recess26having the tournament branch shape is formed in the inner surface12aof the cover member12to be joined with the partition wall17. The cover member12is placed to cover the partition wall17such that the inner surface12aof the cover member12overlaps with the one side surface (the upper surface17b) of the partition wall17to form the gas passage24. Thus, the gas passage24can be more easily formed than the gas passage24formed by only the body casing11. Furthermore, since the partition wall17is formed with no recess, the partition wall17has no portion projected into the hot-water passage31. Thus, the EGR gas distributor1can be easily designed with a desired configuration without increasing its dimension and further can eliminate the pressure loss of hot water due to a projected portion of the partition wall17.

The present disclosure is not limited to each of the aforementioned embodiments and may be embodied in other specific forms without departing from the essential characteristics thereof.

In each of the foregoing embodiments, the EGR gas distributor1is used to distribute EGR gas to each of the branch pipes4A to4D of the intake manifold2. As an alternative, this EGR gas distributor1may be used to distribute auxiliary gas (e.g., PCV gas) other than EGR gas to each of the branch pipes4A to4D of the intake manifold2.

In each of the foregoing embodiments, the hot-water inflow casing13and the hot-water outflow casing14each having a substantially triangular shape in planar view are fixed to both ends of the body casing11in the longitudinal direction to close the openings at both ends. As an alternative, the openings of the body casing at both ends in the longitudinal direction may be closed with simple flat plates. In addition, the shape and the size of the EGR gas distributor may be appropriately changed.

In each of the foregoing embodiments, the EGR gas distributor1is configured to adapt to the intake manifold2with four branch pipes4A to4C. The EGR gas distributor, however, can be configured irrespective of the number of branch pipes.

In each of the foregoing embodiments, the heating part16is constituted of the hot-water passage part18. As an alternative, the heating part may be constituted of an electric heater.

In each of the foregoing embodiments, the cooling water of an engine is used as the hot water allowed to flow through the hot-water passage part18. As an alternative, any hot water other than the engine cooling water may be used.

In the first embodiment, the recess25is provided in the partition wall17and the recess26is provided in the cover member12to form the gas passage24. As an alternative, the recess in the cover member may be dispensed with.

INDUSTRIAL APPLICABILITY

The present disclosure is utilizable in an EGR device and a PCV device provided in an engine system.

REFERENCE SIGNS LIST