JP2021148060A - Protection structure for compressor - Google Patents

Abstract

To protect a compressor from a collision of foreign matter such as ice etc.SOLUTION: A protection structure for a compressor 42 provided in an intake flow passage of an engine 10 to pump intake air, where return flow passages 51, 63 for returning at least exhaust air of the engine 10 to the intake flow passage 21 are connected on an upstream side of the intake flow passage 21 from the compressor 42, and water retention members 71, 72 which absorb and retain water are provided in the flow passage between a connection part of the intake flow passage 21 for the return flow passages 51, 63, and the compressor 42.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a compressor protection structure, and more particularly to a compressor protection structure provided in an intake flow path of an engine to pump intake air.

Conventionally, a blow-by gas treatment device (Positive Crankcase Ventilation: hereinafter referred to as a PCV device) that returns the blow-by gas leaked from the combustion chamber through the gap between the cylinder and the piston into the crankcase to the intake system on the upstream side of the compressor. ) Has been widely put into practical use (see, for example, Patent Document 1).

In addition, a wide range of low pressure-exhaust gas recirculation devices (hereinafter referred to as low pressure EGR devices) are used to recirculate the exhaust gas discharged from the engine and passing through the turbine of the turbocharger to the intake system on the upstream side of the compressor. It has been put into practical use (see, for example, Patent Document 2).

JP-A-2017-193963 Japanese Unexamined Patent Publication No. 2011-021561

In an engine equipped with the above-mentioned PCV device or low-pressure EGR device, water such as condensed water contained in blow-by gas or EGR gas may become ice in a low temperature environment. When such ice collides with a compressor rotating at high speed, the compressor may be damaged, and it is desired to effectively protect the compressor from the collision of foreign matter such as ice.

The technique of the present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to effectively protect the compressor from collision with foreign matter such as ice.

The technique of the present disclosure is a protective structure of a compressor provided in an intake flow path of an engine to pump intake air, and at least the exhaust of the engine is sent to the intake passage on the upstream side of the intake passage with respect to the compressor. A recirculation passage for recirculating is connected, and a water retention member capable of absorbing and retaining water is provided in a passage between the connection portion of the intake passage with the recirculation passage and the compressor. And.

Further, the recirculation passage may be a blow-by gas recirculation pipe for recirculating the blow-by gas of the engine to the intake passage.

Further, the recirculation passage may be an exhaust recirculation pipe that recirculates at least a part of the exhaust gas of the engine to the intake passage on the upstream side of the compressor.

Further, it is preferable that the water retention member is provided at the connection portion in the passage of the intake passage.

Further, the water retention member is formed in a cylindrical or annular shape having a through hole having the same diameter as the inner diameter of the passage of the intake passage or a diameter larger than the inner diameter of the passage, and is radially from the inner circumference of the intake passage. It is preferably attached by being fitted into a concave groove that is recessed to the outside.

Further, it is preferable that the water retention member is further provided in the reflux passage.

Further, a compressor housing accommodating the compressor and a bearing housing accommodating a bearing that pivotally supports a rotating shaft connected to the compressor are further provided, and the water-retaining member is between the compressor housing and the bearing housing. It is preferable that the housing is further provided.

According to the technique of the present disclosure, the compressor can be effectively protected from the collision of foreign matter such as ice.

It is a schematic overall block diagram which shows the intake / exhaust system of the engine which concerns on this embodiment. It is a schematic partial cross-sectional view which shows the protection structure of the compressor which concerns on this embodiment. It is a schematic partial cross-sectional view which shows the protection structure of the compressor which concerns on another embodiment. It is a schematic partial cross-sectional view which shows the protection structure of the compressor which concerns on another embodiment. It is a schematic partial cross-sectional view which shows the protection structure of the compressor which concerns on another embodiment.

Hereinafter, the protective structure of the compressor according to the present embodiment will be described with reference to the accompanying drawings. The same parts have the same reference numerals, and their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing an intake / exhaust system of the engine 10 according to the present embodiment.

As shown in FIG. 1, the main body of the engine 10 mainly includes a cylinder block CB, a cylinder head CH, and an oil pan OP.

The oil pan OP stores engine oil. The oil pan OP is attached to the lower part of the crankcase CA provided in the cylinder block CB.

The cylinder block CB is formed with a cylinder C that accommodates the piston P so as to be reciprocating. A crankshaft CS is connected to the piston P via a connecting rod CR. For the sake of illustration, FIG. 1 shows only one of the plurality of cylinders of the engine 10, and the other cylinders are not shown. The engine 10 may be either a plurality of cylinders or a single cylinder.

The cylinder head CH is provided above the cylinder block CB. The combustion chamber is partitioned by the inner wall of the cylinder C, the lower surface of the cylinder head CH, and the top surface of the piston P. A cylinder head cover HC is provided above the cylinder head CH. The cylinder head CH is provided with an intake port 11 for introducing intake air into the combustion chamber and an exhaust port 12 for drawing out exhaust gas from the combustion chamber. Further, the cylinder head CH is provided with an intake valve 13, an exhaust valve 14, an injector 15, and the like. The engine 10 is not limited to the direct injection type shown in the illustrated example, and may be a premixed type engine.

An intake manifold 20 that distributes intake air to each intake port 11 is attached to the side portion of the cylinder head CH on the intake side (right side in the drawing). An intake passage 21 for introducing intake air is connected to the intake manifold 20. The intake passage 21 is provided with an air cleaner 22, a compressor 42 of the turbocharger 40, an intercooler 23, and the like in this order from the upstream side of the intake air.

An exhaust manifold 30 that collects exhaust gas from each exhaust port 12 is attached to the side portion of the cylinder head CH on the exhaust side (left side in the drawing). An exhaust passage 31 for leading out the exhaust is connected to the exhaust manifold 30. The exhaust passage 31 is provided with a turbine 41 of the turbocharger 40, an exhaust throttle valve 85, an exhaust aftertreatment device 80, a silencer (not shown), and the like in this order from the exhaust upstream side.

The exhaust gas aftertreatment device 80 includes an oxidation catalyst 81 and a filter 82 in this order from the upstream side of the exhaust gas.

The oxidation catalyst 81 is formed by supporting a catalyst component or the like on the surface of a ceramic carrier such as a cordierite honeycomb structure. When unburned fuel (hydrocarbon: HC) is supplied by the post-injection of the engine 10 or the exhaust pipe injection of an exhaust pipe injector (not shown), the oxidation catalyst 81 oxidizes the unburned fuel (hydrocarbon: HC) to raise the exhaust temperature.

The filter 82 is formed, for example, by arranging a large number of cells partitioned by a porous partition wall along the flow direction of exhaust gas, and alternately sealing the upstream side and the downstream side of these cells. .. The filter 82 collects particulate matter (PM) in the exhaust gas in the pores and surface of the partition wall, and when the amount of PM accumulated reaches a predetermined amount, the filter regeneration is carried out to burn and remove the particulate matter (PM). Will be done. At the time of filter regeneration, preferably, the exhaust throttle valve 85 is throttled to the closed side to prevent the temperature of the oxidation catalyst 81 from dropping.

The turbocharger 40 includes a turbine 41 that is rotationally driven by exhaust gas, and a compressor 42 that is connected to the turbine 41 via a turbo shaft 43 (rotary shaft) to pump intake air. The turbocharger 40 is not limited to the conventional type shown in the illustrated example, and may be a variable capacitance type having variable wings.

The low-pressure EGR device 50 includes a low-pressure EGR pipe 51 (an example of the recirculation passage of the present disclosure) that branches from the exhaust passage 31 on the downstream side of the exhaust gas from the turbine 41 and joins the intake passage 21 on the upstream side of the compressor 42. An EGR cooler 52 provided in the low-pressure EGR pipe 51 to cool the EGR gas and an EGR valve 53 for adjusting the recirculation amount of the EGR gas are provided. The low-pressure EGR pipe 51 may branch from the exhaust passage 31 on the downstream side of the exhaust aftertreatment device (not shown).

The PCV device 60 derives blow-by gas (combustion gas (exhaust) or unburned air-fuel mixture that has become high pressure in the combustion stroke) from the crankcase CA. Specifically, the PCV device 60 includes an oil separator 61, a blow-by gas outlet pipe 62, a blow-by gas recirculation pipe 63 (an example of the recirculation passage of the present disclosure), and an oil return pipe 65.

The blow-by gas outlet pipe 62 connects the blow-by gas outlet portion of the crankcase CA and the blow-by gas inlet portion of the oil separator 61. The blow-by gas lead-out pipe 62 introduces the blow-by gas leaked into the crankcase CA from the combustion chamber side through the gap between the piston P and the inner wall of the cylinder C into the oil separator 61.

The oil separator 61 is a separator that separates blow-by gas and oil into gas and liquid by, for example, colliding the blow-by gas with a collision plate (not shown) and adhering the oil contained in the blow-by gas to the collision surface of the collision plate. Functions as.

The blow-by gas recirculation pipe 63 connects the blow-by gas outlet portion of the oil separator 61 to the intake passage 21 on the intake upstream side of the compressor 42. The blow-by gas recirculation pipe 63 is preferably provided with a check valve 64 for preventing the back-flow of the blow-by gas to the oil separator 61 side.

The oil return pipe 65 connects the oil outlet portion of the oil separator 61 and the oil inlet portion of the crankcase CA. At least a part of the oil separated from the blow-by gas by the oil separator 61 is returned to the oil pan OP via the oil return pipe 65.

In the present embodiment, in order to protect the compressor 42 from collision with foreign matter such as ice at a predetermined portion of the intake flow path 21 (for example, a connection portion with the low pressure EGR pipe 51 and a connection portion with the blow-by gas recirculation pipe 63). Protective structure 70 is provided. Hereinafter, the details of the protective structure 70 will be described.

[Protective structure]
FIG. 2 is a schematic partial cross-sectional view showing a protective structure 70 of the compressor 42 according to the present embodiment. In the figure, reference numeral 44 indicates a compressor housing containing the compressor 42, and reference numeral 49 indicates a bearing housing containing the bearing 49A that pivotally supports the turbo shaft 43. A seal member S for sealing the turbo shaft 43 is provided between the compressor housing 44 and the bearing housing 49.

The compressor housing 44 has a substantially cylindrical intake inlet portion 45, a compressor chamber 46 rotatably accommodating the compressor 42, and a scroll flow path 47 formed in a substantially annular shape surrounding the compressor chamber 46 in order from the intake upstream side. And an intake outlet 48 extending radially outward from the scroll flow path 47. At the upstream end opening of the intake inlet portion 45, the downstream end opening of the intake passage 21 to which the low pressure EGR pipe 51 and the blow-by gas recirculation pipe 63 are connected is fastened and fixed by bolts and nuts (not shown).

That is, the fresh air (intake) that has passed through the air cleaner 22, the EGR gas that is recirculated from the low-pressure EGR pipe 51, and the blow-by gas that is recirculated from the blow-by gas recirculation pipe 63 are sent from the intake passage 21 to the intake inlet portion 45 of the turbocharger 40. be introduced. The intake air, EGR gas, and blow-by gas introduced into the intake inlet portion 45 are pressurized by the compressor 42 rotating inside the compressor chamber 46 and flow into the scroll flow path 47, and are pressure-fed from the scroll flow path 47 to the intake outlet portion 48. It is supposed to be done.

The protective structure 70 includes a first water retention member 71 and a second water retention member 72. These water retention members 71 and 72 are formed in a mesh shape or a porous shape, for example, with metal, resin, or the like, and absorb and retain water such as condensed water flowing into the intake passage 21. Further, the water retention members 71 and 72 are formed substantially in a cylindrical shape or an annular shape, and through holes 71A and 72A for passing intake air are formed through in the axial direction.

Each of the water retention members 71 and 72 is attached to the intake passage 21 by being fitted into an annular concave groove that is recessed radially outward from the inner circumference of the intake passage 21. The inner diameters of the through holes 71A and 72A of the water retention members 71 and 72 are preferably formed to have substantially the same diameter as the inner diameter of the intake passage 21 or a diameter larger than the inner diameter of the intake passage 21 and are introduced into the compressor 42. The pressure loss of the intake air can be effectively suppressed.

The first water retention member 71 is provided at a connection portion where the blow-by gas recirculation pipe 63 of the intake passage 21 joins. Specifically, the first water retention member 71 is integrally provided from immediately upstream to immediately downstream of the connection portion where the blow-by gas recirculation pipe 63 joins, and is provided at a predetermined portion (substantially intermediate) in the tubular axis direction. The through hole through which the blow-by gas recirculation pipe 63 is inserted is formed through in the radial direction.

That is, the moisture contained in the blow-by gas flowing from the blow-by gas recirculation pipe 63 to the intake passage 21 when the engine 10 is operated and the condensed water flowing down from the blow-by gas recirculation pipe 63 when the engine 10 is stopped are effective on the first water retention member 71. It is configured so that it can be absorbed and held (preventing outflow to the downstream side).

Moisture such as condensed water absorbed by the first water retention member 71 is retained by the first water retention member 71 at the time of cold start, evaporates as the engine 10 warms up, becomes a gas, and is introduced into the compressor housing 44. Become so. As a result, it becomes possible to prevent the moisture in the blow-by gas from becoming ice in a low temperature environment and colliding with the compressor 42, and it is possible to effectively prevent the compressor 42 from being damaged due to the collision of ice or the like. It will be possible.

The second water retention member 72 is provided at a connection portion where the low pressure EGR pipe 51 of the intake passage 21 joins. Specifically, the second water retention member 72 is integrally provided from immediately upstream to immediately downstream of the connection portion where the low-pressure EGR pipe 51 joins, and is provided at a predetermined portion (substantially intermediate) in the tubular axis direction. , A through hole through which the low-pressure EGR pipe 51 is inserted is formed through in the radial direction.

That is, the water contained in the EGR gas flowing from the low-pressure EGR pipe 51 into the intake passage 21 when the low-pressure EGR device 50 is operated, and the condensed water flowing down from the low-pressure EGR pipe 51 when the low-pressure EGR pipe 51 is stopped are collected from the second water-retaining member 72. It is configured so that it can be effectively absorbed and held (preventing the outflow to the downstream side).

Moisture such as condensed water absorbed by the second water retention member 72 is retained by the second water retention member 72 at the time of cold start, evaporates as the engine 10 warms up, becomes a gas, and is introduced into the compressor housing 44. Become so. As a result, it becomes possible to prevent the moisture in the EGR gas from becoming ice in a low temperature environment and colliding with the compressor 42, and it is possible to effectively prevent damage to the compressor 42 due to collision with ice or the like. It will be possible. In addition, the operating rate of the low-pressure EGR device 50 can be increased from the time of cold start, and the exhaust emission performance can be effectively improved.

[others]
The present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, the water retention members 71 and 72 have been described as being provided in the intake passage 21, but as shown in FIG. 3, the third water retention member 73 may be provided at a predetermined portion of the blow-by gas recirculation pipe 63. .. If the third water retention member 73 is provided in the blow-by gas recirculation pipe 63, it is possible to effectively prevent the blow-by gas recirculation pipe 63 from being blocked due to freezing of the condensed water in the blow-by gas recirculation pipe 63. ..

Further, although detailed illustration is omitted, it is also possible to provide the third water retention member 73 in the low pressure EGR pipe 51.

Further, as shown in FIG. 4, the fourth water retention member 74 can be provided between the compressor housing 44 and the bearing housing 49. With this configuration, for example, when the filter is regenerated or the exhaust brake is activated, the exhaust pressure rises due to the narrowing of the exhaust passage 31, and the exhaust gas passes through the seal member S and leaks to the compressor housing 44 side. Even in this case, the moisture contained in the exhaust can be effectively absorbed by the fourth water retention member 74.

Further, as shown in FIG. 5, a plurality of water retention members 71, 72, 73, 74 may be arranged in the intake passage 21 on the upstream side of the compressor 42. With this configuration, it becomes possible to absorb water such as condensed water in a stepwise manner, and it becomes possible to more reliably protect the compressor 42.

Further, the first water retention member 71 is directly downstream of the connection portion where the blow-by gas recirculation pipe 63 of the intake passage 21 joins, and the second water retention member 72 is directly downstream of the connection portion where the low pressure EGR pipe 51 of the intake passage 21 joins. It is also possible to provide and configure in.

Further, although the protection structure 70 of the present disclosure has described the compressor 42 of the turbocharger 40 driven by exhaust energy as an example, it can also be applied to the protection of a compressor such as a supercharger driven by the power of an engine 10 or a motor. It is possible.

10 Engine 21 Intake passage 40 Turbocharger 41 Turbine 42 Compressor 43 Turbo shaft 44 Compressor housing 49 Bearing housing 51 Low pressure EGR passage (recirculation passage)
63 Blow-by gas recirculation pipe (recirculation passage)
70 Protective structure 71 1st water retention member 72 2nd water retention member

Claims (7)

It is a protective structure of the compressor that is installed in the intake flow path of the engine and pumps the intake air.
A recirculation passage for returning at least the exhaust gas of the engine to the intake passage is connected to the upstream side of the intake passage with respect to the compressor.
A compressor protection structure, characterized in that a water retention member capable of absorbing and retaining water is provided in a passage between the connection portion of the intake passage with the reflux passage and the compressor. The compressor protection structure according to claim 1, wherein the recirculation passage is a blow-by gas recirculation pipe that recirculates the blow-by gas of the engine to the intake passage. The compressor protection structure according to claim 1, wherein the reflux passage is an exhaust recirculation pipe that recirculates at least a part of the exhaust gas of the engine to the intake passage on the upstream side of the compressor. The compressor protection structure according to any one of claims 1 to 3, wherein the water retention member is provided at the connection portion in the passage of the intake passage. The water retention member is formed in a cylindrical or annular shape having a through hole having the same diameter as the inner diameter of the passage of the intake passage or a diameter larger than the inner diameter of the passage, and is formed radially outward from the inner circumference of the intake passage. The protective structure for a compressor according to any one of claims 1 to 4, which is attached by being fitted into a recessed groove. The compressor protection structure according to any one of claims 1 to 5, wherein the water retention member is further provided in the return passage. A compressor housing accommodating the compressor and a bearing housing accommodating a bearing for supporting a rotating shaft connected to the compressor are further provided.
The compressor protection structure according to any one of claims 1 to 6, wherein the water retention member is further provided between the compressor housing and the bearing housing.

Images