Muffler for internal combustion engines

Patent metadata

Field	Value
Publication number	US-2024384673-A1
Application number	US-202218689487-A
Country	US
Kind code	A1
Filing date	Sep 26, 2022
Priority date	Sep 29, 2021
Publication date	Nov 21, 2024
Grant date	—

Abstract

A muffler ( 4 ) for motor vehicles comprising an intake pipe ( 8 ) of the exhaust gases that separates, at a fork ( 10 ), into a main pipe ( 12 ) and a secondary pipe ( 16 ), a muffler body ( 24 ) which delimits an expansion volume ( 28 ) and houses at least partly the main pipe ( 12 ) and the secondary pipe ( 16 ), wherein the intake pipe ( 8 ) of the exhaust gas is in fluid continuous connection with the main pipe ( 12 ) through the secondary pipe ( 16 ), and wherein the main pipe ( 12 ) comprises, downstream of the fork ( 10 ), a throttle valve ( 32 ) which allows or prevents a further fluidic connection of the intake pipe ( 8 ) of exhaust gas with the main pipe ( 12 ), and an output of the exhaust gases ( 40 ), for the expulsion of the gases from the muffler pipe ( 4 ).

First claim

1 . A muffler for internal combustion engines, comprising:
an intake pipe for the exhaust gases with an intake port for the exhaust gases adapted to be fluidly coupled to an internal combustion engine; wherein the intake pipe for the exhaust gases separates, at a fork, into a main pipe and a secondary pipe; a muffler body that delimits an expansion volume and houses at least partially the main pipe and the secondary pipe; wherein the secondary pipe has a distal end that is arranged opposite the fork and ends in the expansion volume; and wherein the main pipe has a distal end that is arranged opposite the fork and forms an outlet for the exhaust gases ending outside the expansion volume to expel the exhaust gases; a throttle valve provided in the main pipe and adapted selectively to allow the exhaust gases to enter, or to prevent them from entering, the main pipe; and a catalyst device provided in the intake pipe for the exhaust gases, between the intake port and the fork; wherein: between the catalyst device and the throttle valve, the main pipe comprises a wall portion, which is provided with a plurality of inlet holes arranged around an axis of the wall portion; the wall portion is surrounded by an outer sleeve; the outer sleeve and the wall portion define an annular chamber surrounding the wall portion; the annular chamber is fluidly coupled to the main pipe through the inlet holes and to the secondary pipe through at least one passage provided in the outer sleeve.

2 . The muffler of claim 1 , comprising a connection path between the secondary pipe and the main pipe inside the muffler body; wherein the connection path is adapted to allow the exhaust gases to flow from the secondary pipe into the main pipe.

3 . The muffler of claim 1 , wherein the inlet holes are provided around the axis of the wall portion spaced from one another by a constant distance or a constant angular pitch.

4 . The muffler of claim 1 , wherein the wall portion has a tapered shape from an intake end facing the catalyst device towards an outlet end facing the throttle valve.

5 . The muffler of claim 1 , wherein the catalyst device has an intake opening and an exhaust opening for the exhaust gases, and wherein the exhaust opening of the catalyst device is provided at a distance from the throttle valve that is shorter than four times the maximum dimension of the cross section of the catalyst device and preferably shorter than three times the maximum dimension of the cross section of the catalyst device.

6 . The muffler of claim 1 , wherein the catalyst device has an intake opening and an exhaust opening for the exhaust gases, and wherein the exhaust opening of the catalyst device is provided at a distance from the fork that is shorter than three times the maximum dimension of the cross section of the catalyst device, and preferably shorter than two times the maximum dimension, more preferably equal to, or shorter than, the maximum dimension.

7 . The muffler of claim 1 , wherein the inlet holes are so configured and arranged that, in use, when the throttle valve is at least partially closed, the exhaust gases flow through the entire cross section of the catalyst device, preferably with a volumetric flow rate that is approximately constant at each point of the cross section of the catalyst device.

8 . The muffler of claim 1 , wherein the inlet holes are so configured and arranged that, in use, when the throttle valve is closed, the flow of the exhaust gases is approximately constant in the entire useful cross section of the catalyst device.

9 . The muffler of claim 1 , wherein the inlet holes are so configured that each of them defines a respective path between the exhaust opening of the catalyst device and the secondary pipe, wherein, in use, the exhaust gases are subjected to a pressure drop that is approximately equal in each path.

10 . The muffler of claim 1 , wherein each inlet hole has a cross section having an area that varies as a function of the distance between the inlet hole and the at least one passage in the outer sleeve that is closer thereto, the area increasing as the distance increases.

11 . The muffler of claim 1 , comprising at least four, preferably at least six, and more preferably at least eight inlet holes.

12 . A motor vehicle comprising an internal combustion engine and a muffler, the muffler fluidly coupled to an exhaust of the internal combustion engine; wherein the muffler comprises:
an intake pipe for the exhaust gases with an intake port for the exhaust gases adapted to be fluidly coupled to an internal combustion engine; wherein the intake pipe for the exhaust gases separates, at a fork, into a main pipe and a secondary pipe; a muffler body that delimits an expansion volume and houses at least partially the main pipe and the secondary pipe; wherein the secondary pipe has a distal end that is arranged opposite the fork and ends in the expansion volume; and wherein the main pipe has a distal end that is arranged opposite the fork and forms an outlet for the exhaust gases ending outside the expansion volume to expel the exhaust gases; a throttle valve provided in the main pipe and adapted selectively to allow the exhaust gases to enter, or to prevent them from entering, the main pipe; and a catalyst device provided in the intake pipe for the exhaust gases, between the intake port and the fork; wherein: between the catalyst device and the throttle valve, the main pipe comprises a wall portion, which is provided with a plurality of inlet holes arranged around an axis of the wall portion: the wall portion is surrounded by an outer sleeve; the outer sleeve and the wall portion define an annular chamber surrounding the wall portion; the annular chamber is fluidly coupled to the main pipe through the inlet holes and to the secondary pipe through at least one passage provided in the outer sleeve.

13 . The motor vehicle of claim 12 , wherein the motor vehicle is a saddle vehicle.

Assignees

• Piaggio & C Spa

Inventors

• Magherini Adriano

Classifications

• F01N2590/04

  for motorcycles · CPC title

• F01N1/082 Primary

  by passing the exhaust gases through porous members · CPC title

• F01N2470/24

  Concentric tubes or tubes being concentric to housing, e.g. telescopically assembled · CPC title

• F01N2470/20

  Dimensional characteristics of tubes, e.g. length, diameter · CPC title

• F01N2470/04

  characterised by shape, disposition or dimensions of apertures · CPC title