Acoustic insulation system for internal combustion engine

An acoustic insulation system for an internal combustion engine mounted on a vehicle according to the present disclosure includes: an acoustic insulation cover configured to cover the internal combustion engine with a gap interposed between the acoustic insulation cover and the internal combustion engine; a first fan configured to introduce air toward the interior of the acoustic insulation cover; and a second fan configured to discharge air from the interior of the acoustic insulation cover.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of Japanese Patent Application No. 2018-079351, filed on Apr. 17, 2018, which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to an acoustic insulation system for an internal combustion engine.

Background Art

For example, JP 2017-013638 A discloses a cooling control structure for an engine compartment. This cooling control structure is provided with a heat retention cover that covers the periphery of an internal combustion engine arranged in the engine compartment.

More specifically, one inlet and one outlet of cooling wind are each formed in the heat retention cover. In addition, an inlet opening/closing portion for adjusting the intake amount of the cooling wind is provided at a formation portion of the inlet, and an outlet opening/closing portion for adjusting the discharge amount of the cooling wind is provided at a formation portion of the outlet.

SUMMARY

According to the cooling control structure for the engine compartment disclosed in JP 2017-013638 A, a relative wind produced during running of a vehicle on which the internal combustion engine is mounted is used as the above-described cooling wind for cooling the internal combustion engine. During stop of the vehicle, the relative wind cannot be used. Thus, it becomes difficult to efficiently perform ventilation of the interior of the heat retention cover. In this respect, the structure disclosed in JP 2017-013638 A still has room for improvement in terms of achieving efficient ventilation of the interior of the heat retention cover when the relative wind cannot be used.

The present disclosure has been made to address the problem described above, and an object of the present disclosure is to provide an acoustic insulation system for an internal combustion engine that can efficiently perform ventilation of the interior of an acoustic insulation cover that covers an internal combustion engine even when relative wind cannot be used.

An acoustic insulation system for an internal combustion engine according to the present disclosure is applied to an internal combustion engine mounted on a vehicle. The acoustic insulation system includes: an acoustic insulation cover configured to cover the internal combustion engine with a gap interposed between the acoustic insulation cover and the internal combustion engine; a first fan configured to introduce air toward an interior of the acoustic insulation cover; and a second fan configured to discharge air from the interior of the acoustic insulation cover.

The acoustic insulation cover may include an opposed portion that is opposed to the second fan. The opposed portion may also include an opening portion and a flap configured to open and close the opening portion.

The flap may be configured to close during operation of the internal combustion engine and open during stop of the internal combustion engine.

The first fan and the second fan may be integrally arranged in parallel with a bulkhead interposed between the first fan and the second fan. The bulkhead may also be formed so as to protrude toward the internal combustion engine and separate a flow of air by the first fan from a flow of air by the second fan. The second fan may be further configured to blow air in a direction opposite to a flow direction of air by the first fan.

The first fan and the second fan may be integrally arranged in parallel with a bulkhead interposed between the first fan and the second fan. The bulkhead may also be formed so as to separate a flow of air by the first fan from a flow of air by the second fan. The flap may be further configured to close during operation of the internal combustion engine and open during stop of the internal combustion engine. The second fan may be further configured, during the stop of the internal combustion engine, to blow air in a direction opposite to a flow direction of air by the first fan.

The internal combustion engine may include a portion which is not covered by the acoustic insulation cover. The first fan may also be opposed to the internal combustion engine at the portion which is not covered by the acoustic insulation cover.

According to the acoustic insulation system for an internal combustion engine of the present disclosure, air can be introduced toward the interior of the acoustic insulation cover by the use of the first fan, and air can be discharged from the interior of the acoustic insulation cover by the use of the second fan. Thus, according to the acoustic insulation system of the present disclosure, even when, since the internal combustion engine is stopped and the vehicle is also stopped accordingly, the relative wind cannot be used, ventilation of the interior of the acoustic insulation cover can be efficiently performed.

DETAILED DESCRIPTION

In the following, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it is to be understood that even when the number, quantity, amount, range or other numerical attribute of an element is mentioned in the following description of the embodiments, the present disclosure is not limited to the mentioned numerical attribute unless explicitly described otherwise, or unless the present disclosure is explicitly specified by the numerical attribute theoretically. Furthermore, structures or the like that are described in conjunction with the following embodiments are not necessarily essential to the present disclosure unless explicitly shown otherwise, or unless the present disclosure is explicitly specified by the structures or the like theoretically.

1. First Embodiment

1-1. Configuration of Acoustic Insulation System

1-1-1. Configuration of Internal Combustion Engine and Therearound

FIG. 1is a diagram (vehicle side view) that schematically illustrates the configuration of an internal combustion engine20to which an acoustic insulation system10according to the first embodiment of the present disclosure is applied and around the internal combustion engine20. As shown inFIG. 1, the internal combustion engine20is mounted on a vehicle1. In more detail, the internal combustion engine20is installed in an engine compartment2of the vehicle1.

InFIG. 1, the upper side of the sheet corresponds to the front side of the vehicle1, and the left side of the sheet corresponds to the upper side of the vehicle1. An engine hood3is arranged at the vehicle upper side of the internal combustion engine20. A radiator4and cooling fans (first fan52and second fan54described later) are arranged at the vehicle front side of the internal combustion engine20. In addition, an engine lower cover5is arranged at the vehicle lower side of the internal combustion engine20, and a bulkhead7(such as, cowl top panel and dash panel) that separates the engine compartment2from a vehicle interior6is arranged at the vehicle rear side. It should be noted that vehicle components (not shown), such as a suspension tower, are arranged at both the vehicle-left-and-right sides of the internal combustion engine20.

In the example shown inFIG. 1, the internal combustion engine20is mounted on the vehicle1such that the axial direction of a crankshaft22coincides with the left-right direction of the vehicle1. Also, in the example shown inFIG. 1, the internal combustion engine20is mounted on the vehicle1such that intake system parts including an intake manifold24are located on the vehicle front side and exhaust system parts including an exhaust manifold26are located on the vehicle rear side.

Moreover, the internal combustion engine20is equipped with an engine main body28. The engine main body28includes a cylinder head (including a cylinder head cover)30, a cylinder block (including a crankcase)32and an oil pan34in addition to the crankshaft22described above. The cylinder head30is installed on the cylinder block32. The oil pan34is arranged below the cylinder block32. An engine lubricating oil that lubricates individual portions of the internal combustion engine20is stored in the interior of the oil pan34.

Furthermore, the internal combustion engine20is equipped with an alternator36and a compressor (hereunder, an “A/C compressor”)38of an air conditioner for the vehicle interior6. The alternator36performs electric power generation by the use of a torque of the crankshaft22. The A/C compressor38supplies refrigerant for the air conditioner by the use of the torque of the crankshaft22.

1-1-2. Configuration of Acoustic Insulation Cover (Acoustic Insulation Structure)

As shown inFIG. 1, the acoustic insulation system10according to the present embodiment is provided with an acoustic insulation cover40. Hereunder, the configuration of the acoustic insulation cover40will be described in detail with additional reference toFIGS. 2 and 3as well asFIG. 1.FIGS. 2 and 3are each schematic diagrams (perspective view and vehicle front view) that illustrate the internal combustion engine20covered by the acoustic insulation cover40.

The acoustic insulation cover40is configured by a material having a high acoustic absorption performance. Moreover, as the material of the acoustic insulation cover40, a material having a certain level of stiffness is used. An example of the material of the acoustic insulation cover40that satisfies this kind of requests is a fibrous material made of PET (Polyethylene terephthalate) fiber. It should be noted that, although the manner of attachment of the acoustic insulation cover40to the internal combustion engine20is not particularly limited, the acoustic insulation cover40is attached to the internal combustion engine20using, as an example, a fastener (such as bolts) which is not shown.

According to the example shown inFIG. 1, the acoustic insulation cover40is configured by two cover pieces42and44divided from each other. The acoustic insulation cover40(each of the cover pieces42and44) covers the internal combustion engine20with a gap interposed between the acoustic insulation cover40and the internal combustion engine20.

To be more specific, as shown inFIGS. 1 to 3, the cover piece42is formed so as to cover a part of an upper portion of the internal combustion engine20and a portion thereof located on the vehicle front side. In detail, the cover piece42mainly covers an upper portion of the engine main body28, and a part of respective portions of the intake manifold24and the engine main body28(cylinder block32) located on the vehicle front side (i.e., a portion located on the vehicle left side in the vehicle front view). In other words, according to the example of the acoustic insulation cover40, portions of the intake manifold24and the engine main body28(cylinder block32) located on the vehicle right side in the vehicle front view, and the alternator36and the A/C compressor38are not covered by the acoustic insulation cover40including the cover piece42.

On the other hand, as shown inFIGS. 2 and 3, the cover piece44is formed so as to cover a major part (mainly, cylinder block32) of a portion (side end surface) of the engine main body28located on the vehicle right side.

Furthermore, as shown inFIGS. 2 and 3, the acoustic insulation cover40includes an opening portion46and a movable flap48operative to open and close the opening portion46. In detail, the opening portion46is formed at a portion of the cover piece42located on the vehicle front side. The flap48is of an electrically-driven type, as an example, and is driven to open and close by an electric motor50.FIG. 3shows a closed state of the flap48. In this state, the flap48functions as a part of the cover piece42. If the flap48is opened, a part of the portions of the intake manifold24and the engine main body28(cylinder block32) located on the vehicle left side in the vehicle front view is exposed to the engine compartment2at the opening portion46.

1-1-3. First and Second Fans

The acoustic insulation system10further includes a first fan52and a second fan54. As described below, the first fan52has a function that introduces air (outside air) toward the interior of the acoustic insulation cover40, and the second fan54has a function that discharges air from the interior of the acoustic insulation cover40. As shown inFIG. 1, the first and second fans52and54are attached to a portion of the radiator4located on the vehicle rear side in the engine compartment2. Because of this, the first and second fans52and54according to the present embodiment have not only the above-described function in the acoustic insulation system10but also a function that supplies the radiator4with a cooling wind.

FIGS. 4A and 4Bare diagrams that schematically illustrate the configuration of the first and second fans52and54and the vicinity thereof.FIG. 4Acorresponds to a vehicle front view andFIG. 4Bcorresponds to a vehicle top view. As shown in these diagrams, the first fan52and the second fan54are integrally arranged in parallel with a bulkhead56interposed therebetween. In more detail, the first and second fans52and54are arranged in parallel along the left-right direction of the vehicle1.

The first and second fans52and54are axial flow electric fans, and are respectively driven by electric motors (not shown). The air blowing direction (i.e., flow direction of air) of the first fan52and the air blowing direction (i.e., flow direction of air) of the second fan54are parallel to each other as shown inFIG. 4B.

To be more specific, the first fan52is arranged and configured so as to blow air toward the internal combustion engine20located on the vehicle rear side relative to the first fan52. The flow direction of air toward the internal combustion engine20from the fans52and54, and the rotational direction of the fans52and54at the time of the flow of air being generated in this flow direction are herein both referred to as “forward direction”.

The second fan54is arranged and configured such that, when rotating in its forward direction, the second fan54blows air toward the vehicle rear side (i.e., the side of the internal combustion engine20) similarly to the first fan52. Also, the second fan54is configured to be rotatable in the direction opposite to the forward direction described above. Because of this, the second fan54can also blow air in the direction opposite to the flow direction of air by the first fan52.

The bulkhead56is formed, as an example, into a plate shape, and is formed so as to protrude toward the internal combustion engine20(i.e., toward the vehicle rear side) and separate the air flow by the first fan52from the air flow by the second fan54. In other words, the bulkhead56is formed so as to extend along the flow directions of air by the first and second fans52and54. With this kind of bulkhead56arranged, when the first and second fans52and54are actuated such that the air blowing directions thereof are opposite to each other, occurrence of a phenomenon in which the wind by the first fan52is sucked out by the second fan54to the side of the radiator4before the wind is reached to the internal combustion engine20can be reduced.

Moreover, as can be well understood with reference toFIGS. 6 and 7described later, the portion of the cover piece42located on the vehicle front side where the opening portion46and the flap48are arranged is opposed to the second fan54. Because of this, this portion corresponds to an example of the “opposed portion” according to the present disclosure.

In further addition to the above, according to the acoustic insulation system10, the first fan52is opposed to the internal combustion engine20at a portion located on the vehicle front side that is not covered by the acoustic insulation cover40(more specifically, the cover piece42). As a result, the first fan52is opposed to the alternator36and the A/C compressor38. The first fan52is also opposed to the respective portions of the intake manifold24and the engine main body28(cylinder block32) located on the vehicle right side in the vehicle front view.

1-1-4. Control Device

The acoustic insulation system10according to the present embodiment is further provided with a control device60for controlling the flap48(electric motor50), and the first and second fans52and54. The control device60is an electronic control unit (ECU) that includes at least one processor, at least one memory, and an input/output interface.

The input/output interface receives sensor signals from a sensor used for determination as to whether the internal combustion engine20is in operation or is stopped, and also outputs actuating signals to the flap48(electric motor50) and the first and second fans52and54which correspond to actuators. An example of the above-mentioned sensor is a crank angle sensor which is not shown. The control device60can calculate an engine speed by the use of crank angle signals from the crank angle sensor. The determination described above can be performed as follows, for example. That is to say, when the engine speed is not zero, it can be determined that the internal combustion engine20is in operation, and, on the other hand, when the engine speed is zero, it can be determined that the internal combustion engine20is stopped.

In the memory of the control device60, various programs and various data (including maps) for controlling the acoustic insulation system10are stored. The processor executes the programs stored in the memory. As a result, various functions of the control device60(such as, introduction of air into the acoustic insulation cover40, discharge of air from the acoustic insulation cover40, and ventilation of the interior of the acoustic insulation cover40associated therewith) are achieved. It should be noted that the control device60may alternatively be configured with two ECUs that are separately provided for the respective first and second fans52and54.

1-2. Operation of Acoustic Insulation System

1-2-1. Operation During Engine Operation

During operation of the internal combustion engine20, the control device60controls the electric motor50such that the flap48closes. As a result, the opening portion46is closed by the flap48as shown inFIG. 3. Moreover, during engine operation, the second fan54of the first and second fans52and54is mainly used, and the first fan52is additionally used as needed. Furthermore, during engine operation, the second fan54is driven to rotate in the forward direction.

Specifically, when a designated fan operating condition that supplies the radiator4with a cooling wind is met, the control device60actuates the second fan54in such a manner that the second fan54rotates in the forward direction. In addition, if engine load is higher than a designated threshold value when the fan operating condition described above is met, the control device60actuates the first fan52as well as the second fan54.

If the second fan54is actuated, the wind from the second fan54flows toward the vehicle upper side along the portion of the cover piece42located on the vehicle front side where a closed flap48is arranged, and then flows toward the vehicle rear side. That is to say, since the flap48is closed, introduction of the wind from the second fan54into the interior of the acoustic insulation cover40is reduced. In addition, since the flap48is also closed when the second fan54is not actuated during engine operation, introduction of the relative wind into the interior of the acoustic insulation cover40is also reduced during running of the vehicle1.

If, on the other hand, the first fan52is actuated, air blown by the first fan52flows toward the portions of the internal combustion engine20located on the vehicle front side that are not covered by the cover piece42(More specifically, flows toward the alternator36and the A/C compressor38and also the respective portions of the intake manifold24and the engine main body28(cylinder block32) located on the vehicle right side in the vehicle front view). As a result, engine parts which generate heat (for example, alternator36, A/C compressor38, and intake system parts, such as intake manifold24) are cooled by the wind from the first fan52.

Furthermore, in the cylinder block32, a water jacket (not shown) through which engine cooling water flows is formed. Air blown by the first fan52flows around the engine parts described above, and then flows along the cylinder block32, and, as a result, is taken into the interior of the acoustic insulation cover40(i.e., the interior of each of the cover pieces42and44). Also, this air introduced into the interior of the acoustic insulation cover40flows toward the rear side of the vehicle1through a gap between the cover pieces42,44and the cylinder block32, and is then discharged from the acoustic insulation cover40. In the course of air flowing in this way, portions of the cylinder block32located in the vicinity of the water jacket are cooled by this air. Therefore, an excess increase of engine cooling water temperature is also reduced at high load conditions.

1-2-2. Operation During Engine Stop

Next, an operation of the acoustic insulation system10during stop of the internal combustion engine20will be described with reference toFIGS. 5 to 7.FIGS. 5 and 6are diagrams (vehicle front view and vehicle side view) that schematically illustrate the internal combustion engine20with the flap48open.FIG. 7is a diagram that schematically illustrates an air flow that is formed during stop of the internal combustion engine20.

During engine stop, the control device60controls the electric motor50such that the flap48opens. As a result, as shown inFIGS. 5 and 6, the opening portion46is opened by the flap48. Also, during engine stop, the control device60actuates the first and second fans52and54as follows at a designated execution timing (for example, immediately after completion of the engine stop). That is to say, the control device60actuates the first fan52(i.e., rotates the first fan52in the forward direction) over a designated time period, and also actuates the second fan54in such a manner that the second fan54rotates in the direction opposite to the forward direction. In other words, the second fan54is actuated during engine stop so as to blow air in the direction opposite to the flow direction of air by the first fan52.

The operation during engine stop is similar to that during engine operation in terms of air that is blown by the first fan52when the first fan52is actuated as described above during engine stop being taken into the interior of the acoustic insulation cover40(i.e., cover pieces42and44). On that basis, during engine stop, the second fan54is driven to rotate in the direction opposite to the forward direction. As a result, as shown inFIG. 6, air in the acoustic insulation cover40(cover piece42) is sucked out from the opening portion46by the second fan54. In addition, the specification of the second fan54is determined such that, when the second fan54is rotated in the direction opposite to the forward direction in this way, air in the cover piece42can be sucked out through the opening portion46.

As a result of the flap48being opened and the first and second fans52and54being actuated described above, air in the acoustic insulation cover40can form an air flow that circulates as shown by arrows inFIG. 7. In more detail, a part of air blown by the first fan52is taken into the interior of the cover piece42, then flows toward the upper side, and then flows toward the vehicle left side from the vehicle right side through a gap between the upper portion of the cylinder head30and the cover piece42. Thereafter, this air is discharged outside the acoustic insulation cover40through the opening portion46. With the circulating air flow formed inside the cover piece42in this way, the interior of the cover piece42can be ventilated.

Furthermore, the flow of air that is blown by the first fan52includes an air flow that passes through the cover piece44and is discharged outside the cover piece44at the vehicle rear side. With this kind of air flow, the interior of the cover piece44can also be ventilated.

As described so far, according to the first fan52(that is driven to rotate in the forward direction), air can be introduced toward the interior of the acoustic insulation cover40. Also, according to the second fan54, when the second fan54is driven to rotate in the direction opposite to the forward direction, air can be discharged from the interior of the acoustic insulation cover40. According to the acoustic insulation system10of the present embodiment, even when, since the internal combustion engine20is stopped and the vehicle1is also stopped accordingly, the relative wind cannot be used, the ventilation of the interior of the acoustic insulation cover40can be efficiently performed by the use of these fans52and54.

Moreover, according to the ventilation of the interior of the acoustic insulation cover40, the following advantageous effects can be achieved.

(1) Discharge of heat from the interior of the acoustic insulation cover40(including cooling of the internal combustion engine20)

(2) Reduction of erosion of the engine parts associated with facilitation of drying of the interior space (i.e., the gap between the acoustic insulation cover40and the internal combustion engine20) of the acoustic insulation cover40

(3) Reduction of occurrence of unusual odor (due to fuel, engine lubricating oil and water) in the interior of the acoustic insulation cover40associated with the facilitation of drying described above

Moreover, according to the acoustic insulation system10of the present embodiment, the opening portion46of the acoustic insulation cover40(cover piece42) and the flap48are arranged at the opposed portion that is opposed to the second fan54. According to this kind of configuration, a high degree of freedom of formation of an air flow around the acoustic insulation cover40can be achieved by the use of opening and closing of the flap48and switching of the air blowing directions of the second fan54. In detail, by reversely rotating the second fan54when the flap48is open, discharge of air from the interior of the acoustic insulation cover40can be facilitated. Also, if there is a request to cause the second fan54to form an air flow in the forward direction when introduction of air into the interior of the acoustic insulation cover40is not required, the flap48is closed, and thus, the second fan54can be actuated while reducing introduction of air into the interior of the acoustic insulation cover40. Therefore, in an example in which the second fan54has a function as a cooling fan of the radiator4as in the acoustic insulation system10, when there is a request to cause the second fan54to supply a cooling wind as one example of the above-mentioned request during engine operation, the cooling wind can be supplied to the radiator4while reducing the introduction of air into the interior of the acoustic insulation cover40.

Moreover, according to the acoustic insulation system10of the present embodiment, the flap48is configured to close during engine operation and open during engine stop. By opening and closing the flap48as needed in this way, reduction of heat release (cooling) of the internal combustion engine20during engine operation and facilitation of heat release (cooling) of the internal combustion engine20during engine stop can be both achieved. In detail, during engine stop, introduction of a wind from the second fan54or of the relative wind into the interior of the acoustic insulation cover40can be reduced, and the heat release of the internal combustion engine20can thus be reduced. In addition, during engine stop, even when the relative wind cannot be used, the ventilation of the acoustic insulation cover40can be performed by opening the flap38and reversely rotating the second fan54, and the heat release of the internal combustion engine20can thus be facilitated.

Furthermore, according to the acoustic insulation system10of present embodiment, the first fan52and the second fan54are integrally arranged in parallel with the bulkhead56interposed therebetween. The bulkhead56is formed so as to protrude toward the internal combustion engine20and separate the flow of air by the first fan52and the flow of air by the second fan54. Also, the second fan54is configured to be able to blow air in the direction opposite to the flow direction of air by the first fan52. According to this kind of configuration, the first fan52having the function of introducing air toward the interior of the acoustic insulation cover40(i.e., the side of the internal combustion engine20) and the second fan54having the function of discharging air from the interior of the acoustic insulation cover40(i.e., the side of the internal combustion engine20) can be compactly modularized. This is favorable to improve the mounting ability of the first and second fans52and54on the vehicle1.

Additionally, according to the acoustic insulation system10of the present embodiment, the engine parts which generate heat (for example, alternator36, A/C compressor38, and intake system parts, such as intake manifold24) are installed on the engine main body28(cylinder block32). Also, the acoustic insulation system10is configured such that the portions on which (at least one of) these engine parts are installed are not covered by the cover piece42. Moreover, the first fan52is arranged so as to be opposed to these portions. As a result, these engine parts can be efficiently cooled by the use of air that is blown by the first fan52.

2. Other Embodiments

2-1. Other Examples of Installation of First and Second Fans

In the first embodiment described above, the first and second fans52and54are installed on the radiator4. However, the first and second fans may alternatively be installed on any other desired portions in the engine compartment, as long as the first fan is able to introduce air toward the interior of the acoustic insulation cover and the second fan is able to discharge air from the interior of the acoustic insulation cover. Specifically, these fans may be installed on, for example, an acoustic insulation cover, an internal combustion engine or a vehicle body part other than the radiator.

Furthermore, in the first embodiment, the first fan52and the second fan54are integrally arranged in parallel with the bulkhead56interposed therebetween. However, the first fan and the second fan according to the present disclosure may not always be integrally arranged in parallel and alternatively be arranged at respective locations separate from each other. In addition, the number of the first fan is not limited to one and may be plural, and, similarly, the number of the second fan is not limited to one and may be plural.

2-2. Another Example of Acoustic Insulation Cover

In the first embodiment, the opening portion46and the flap48are arranged at the opposed portion of the acoustic insulation cover40that is opposed to the second fan54. However, the “acoustic insulation cover” according to the present disclosure may not always include these opening portion and flap.

Furthermore, contrary to the example of the acoustic insulation cover40, the “acoustic insulation cover” according to the present disclosure may, for example, cover a portion (back surface) of an internal combustion engine located on the vehicle rear side while avoiding exhaust system parts, or cover a portion of an engine main body located on the vehicle left side (i.e., a side end surface of the engine main body located on the side where a transmission or a vehicle-driving motor is arranged). To be more specific, this side end surface may alternatively be covered as a result of the transmission or the vehicle driving motor being covered by a desired cover piece. Also, the acoustic insulation system may alternatively be configured, for example, by the use of, as well as the cover piece44, cover pieces that cover these bask surface and the side end surface, such that a circulating air flow as described with reference toFIG. 7is formed inside the acoustic insulation cover.

The embodiments and modification examples described above may be combined in other ways than those explicitly described above as required and may be modified in various ways without departing from the scope of the present disclosure.