THERMAL INSULATION STRUCTURE FOR INTERNAL COMBUSTION ENGINE

Abstract

Thermal insulation structure for an internal combustion engine (1) which is accommodated in an engine compartment provided on the front of a vehicle and is opened / closed by an engine hood (80), and which comprises a cylinder block (3) and a cylinder head (2) coupled to a top of the cylinder block (3), having the thermal insulation structure: a cylinder head-side thermal insulation cover (30), comprising an upper wall (31) which faces and is spaced apart from the top surface of the cylinder head (2) and which covers an entire top surface of the head, first side walls (32) extending in a longitudinal direction of the vehicle and each facing and spaced apart from a corresponding one of the two side surfaces of the cylinder head (2) in a transverse direction of the vehicle and a corresponding one of the upper sections of both side surfaces of the cylinder block (3) in the transverse direction of the vehicle, and each covering the corresponding one of the two side surfaces of the cylinder head (2) in the transverse direction of the vehicle and the corresponding one of the upper sections of the two side surfaces of the cylinder block (3) in the transverse direction of the vehicle, and Release sections (39) formed at each of the two edges of the cylinder head-side thermal insulation cover (30) in a longitudinal direction of the vehicle; and a cylinder block-side thermal insulation cover (40), comprising a front wall (41) covering a front surface of the cylinder block (3), a rear wall (42) covering a rear surface of the cylinder block (3), and second side walls (43) each covering a corresponding side surface of the cylinder block (3) in the width direction of the vehicle, wherein Each of the first side walls (32) is arranged outwards in the width direction of the vehicle and spaced apart from a corresponding second side wall (43), and a lower edge of each of the first side walls (32) is positioned below an upper edge of the corresponding second side wall (43) so that it overlaps the corresponding second side wall (43) when viewed from one side of the vehicle, characterized by the fact that the cylinder head-side thermal insulation cover (30) is vertically divided into an upper cylinder head-side thermal insulation cover (33) and a lower cylinder head-side thermal insulation cover (34), wherein the upper cylinder head-side thermal insulation cover (33) can be removed from the lower cylinder head-side thermal insulation cover (34), the upper cylinder head-side thermal insulation cover (33) includes the upper wall (31) and upper sections of the first side walls (32) and the lower cylinder head-side thermal insulation cover (34) includes lower sections of the first side walls (32).

Description

TECHNICAL AREA

[0001] The present disclosure relates to a thermal insulation structure of an internal combustion engine, in particular a thermal insulation structure of an internal combustion engine which is accommodated in an engine compartment provided at the front of a vehicle and is opened / closed by an engine hood, and which comprises a cylinder block and a cylinder head coupled to the top of the cylinder block. TECHNICAL BACKGROUND

[0002] Conventional thermal insulation structures for an internal combustion engine, comprising a cylinder block and a cylinder head coupled to the top of the cylinder block, are known from the prior art. JP 2013-11384 discloses a thermal insulation structure for an internal combustion engine, comprising an engine compartment encapsulation element that surrounds the upper section of a powertrain configured as an assembly of an engine (internal combustion engine) and a transmission in an engine compartment, and an underbody encapsulation element that surrounds the lower section of the powertrain.The engine compartment encapsulation element and the underbody encapsulation element are designed such that the engine compartment encapsulation element and the underbody encapsulation element are mounted vertically to each other in a space between the powertrain and a vehicle body surrounding the powertrain, and that air for cooling the powertrain, which flows from an inlet of a front surface where the engine compartment encapsulation element and the underbody encapsulation element are mounted vertically to each other, is discharged from an outlet of a rear surface where the underbody encapsulation element is open.

[0003] A vehicle conforming to US 3882951 A has a sliding engine mounting frame that is relatively flexible relative to the chassis frame. The engine can be quickly separated from the vehicle body. Both the electrical and fluid connections between the engine and the vehicle body are designed to allow for a uniform separation using modular plates attached to the main frame member of the chassis. The vehicle body incorporates sound-dampening insulation surrounding the upper part of the engine. A pivoting element extends across the bottom of the engine to reflect engine noise upward into the sound-dampening insulation. The fan cover is specifically designed to reduce airflow noise. An auxiliary drive shaft for the fan is connected via a flexible coupling and is specifically designed to drive accessory components.

[0004] DE 10 2012 106 644 A1 discloses a structure for an engine encapsulation of a vehicle; comprising an engine compartment encapsulation part arranged on an upper section of an engine compartment and covering an upper section of a drivetrain comprising an engine and a transmission, an underbody encapsulation part arranged on a lower section of the engine compartment and covering a lower section of the drivetrain, wherein the engine compartment encapsulation part and the underbody encapsulation part form an interior space and enclose the drivetrain in the interior space when assembled together, and a front inlet formed on a front section of the assembly arrangement to allow air to flow through the front inlet and cool the drivetrain as the air passes through the interior space of the assembly arrangement, the air being discharged through a rear outlet formed on the assembly arrangement. PRESENTATION OF THE INVENTIONAL PROBLEM

[0005] In the thermal insulation structure of the internal combustion engine as disclosed in JP 2013-11384, the engine compartment encapsulation element and the underbody encapsulation element can thermally insulate the internal combustion engine and the transmission. Furthermore, by allowing headwind to be introduced from the front inlet into each encapsulation element, it is essentially possible to prevent an excessive increase in the temperature of the entire internal combustion engine.

[0006] However, the individual components that make up the internal combustion engine have different types of thermal insulation requirements. For example, a cylinder head, which includes components with low heat resistance, such as a fuel injection system, requires high cooling capacity in addition to thermal insulation performance. Conversely, a cylinder block with cylinders requires that the cylinder temperature be maintained, and therefore thermal insulation performance takes precedence over cooling performance.

[0007] This means that although the thermal insulation structure of the internal combustion engine disclosed in JP 2013-11384 can thermally insulate the internal combustion engine and the transmission, and can also cool the internal combustion engine, it is difficult, for example, to cool the cylinder head and simultaneously thermally insulate the cylinder block.

[0008] The present disclosure was made in consideration of the above tasks and is intended to provide a technique capable of cooling part of an internal combustion engine while thermally insulating the entire internal combustion engine. SOLUTION TO THE TASK

[0009] The present disclosure relates to a thermal insulation structure for an internal combustion engine, in particular a thermal insulation structure for an internal combustion engine that is accommodated in an engine compartment located at the front of a vehicle and is opened / closed by an engine hood, and which comprises a cylinder block and a cylinder head coupled to the top of the cylinder block. The thermal insulation structure comprises: a cylinder head-side thermal insulation cover, with an upper wall facing and spaced apart from the top of the cylinder head and covering the entire top of the head, and first side walls.extending in a longitudinal direction of the vehicle, each facing and spaced apart from a corresponding one of the two side faces of the cylinder head in a transverse direction of the vehicle and a corresponding one of the upper sections of both side surfaces of the cylinder block in the transverse direction of the vehicle, and each covering the corresponding one of the two side faces of the cylinder head in the transverse direction of the vehicle and the corresponding one of the upper sections of the two side faces of the cylinder block in the transverse direction of the vehicle, and release sections formed at each of the two edges of the cylinder head-side thermal insulation cover in a longitudinal direction of the vehicle; and a cylinder block-side thermal insulation cover, comprising a front wall covering a front face of the cylinder block closer to a front of the vehicle, a rear wall,The first side walls cover one rear surface of the cylinder block closer to the rear of the vehicle, and the second side walls each cover a corresponding one of the two side surfaces of the cylinder block in the width direction of the vehicle. Each of the first side walls is arranged outwards in the width direction of the vehicle towards and spaced apart from a corresponding one of the second side walls, and a lower edge of each of the first side walls is positioned below an upper edge of the corresponding one of the second side walls, so that it overlaps a corresponding one of the second side walls when viewed from the side of the vehicle.

[0010] According to this design, cylinder head and cylinder block thermal insulation covers are provided. The cylinder head cover covers the entire upper surface of the cylinder head, both sides of the cylinder head in the width direction of the vehicle, and upper sections of both sides of the cylinder block in the width direction of the vehicle. The cylinder block thermal insulation cover covers the front and rear surfaces of the cylinder block closer to the front and rear of the vehicle, and both sides of the cylinder block in the width direction of the vehicle. Furthermore, the lower section of the first side wall of the cylinder head thermal insulation cover, viewed from the side of the vehicle, overlaps the upper section of the corresponding second side wall of the cylinder block thermal insulation cover.Therefore, the interior of the cylinder head and cylinder block heat insulation covers can be adequately insulated. This enables thermal insulation of the entire internal combustion engine, compared to a case where there are no cylinder head and cylinder block heat insulation covers.

[0011] The heat from cylinder head 2 and cylinder block 3 is dissipated to the air via heat transfer and radiation after the combustion engine is stopped. The air around the cylinder head and cylinder block, heated by this heat transfer, rises and remains within the cylinder head-side heat insulation cover. By positioning the lower edge of the first side wall of the cylinder head-side heat insulation cover below the upper edge of the second side wall, the volume of air contained within the cover can be increased. This allows the cylinder head to be covered with a larger volume of heated air, thus enabling efficient thermal insulation.Furthermore, the lower section of the first side wall and the upper section of the second side wall will overlap when viewed from the side of the vehicle. This overlapping section can provide double shielding from radiation emanating from the cylinder block, thus also efficiently insulating the cylinder block thermally.

[0012] The cylinder head thermal insulation cover is equipped with release sections along both edges in the longitudinal direction of the vehicle. This allows the airflow, when the vehicle is in motion, to flow from the front release section of the cylinder head cover, closer to the front of the vehicle, into the thermal insulation cover and then along the rear release section, which is closer to the rear of the vehicle, to pass through the cover.When the headwind passes through the cylinder head-side thermal insulation cover while the vehicle is in motion, it travels through the gap between the upper wall and the top of the cylinder head, the space between each of the first side walls and the corresponding side faces of the cylinder head in the vehicle's width direction, and the space between each of the first side walls and the corresponding side faces of the cylinder block in the vehicle's width direction. The front face of the cylinder block closer to the front of the vehicle is covered by the front wall of the cylinder block-side thermal insulation cover. Thus, no headwind blows against the front face of the cylinder block closer to the front of the vehicle. Furthermore, each of the first side walls is positioned outwards in the vehicle's width direction and spaced apart from the respective second side walls.Thus, the space between the second side wall and the corresponding side surface of the cylinder block in the vehicle's width direction is narrower than the space between the first side wall and the corresponding side surface of the cylinder block in the vehicle's width direction. Therefore, the headwind has difficulty penetrating this space. Consequently, the cylinder block is less likely to be cooled by the headwind than the cylinder head. As a result, the cylinder block can be kept warm while the cylinder head can be actively cooled.

[0013] Accordingly, it becomes possible to cool part of the combustion engine while thermally insulating the combustion engine as a whole.

[0014] In one embodiment of the thermal insulation structure of the internal combustion engine, in the case of the cylinder block-side thermal insulation cover, the front wall touches the front surface of the cylinder head closer to the front of the vehicle, the rear wall touches the front surface of the cylinder block closer to the rear of the vehicle, and the second walls each touch the corresponding of the two side surfaces of the cylinder head in the width direction of the vehicle.

[0015] This means that if the front wall contacts the front surface of the cylinder block closer to the front of the vehicle, the rear wall contacts the rear surface of the cylinder block closer to the rear of the vehicle, and each of the second walls contacts the corresponding side surface of the cylinder block in the vehicle's width direction, then no headwind will blow against the sections of the cylinder block contacting the top wall, the rear wall, and the second side walls while the vehicle is in motion. Therefore, these sections of the cylinder block are not cooled by the headwind. As a result, the cylinder block-side thermal insulation cover can insulate the cylinder block more efficiently.

[0016] In the thermal insulation structure of the internal combustion engine, it is preferred that a device for controlling exhaust emissions is arranged longitudinally behind the internal combustion engine and below an edge of the upper wall closer to the rear of the vehicle, a space between the cylinder head-side thermal insulation cover and the internal combustion engine forms a flow channel in which headwind flows from the release section closer to the rear of the vehicle during operation, and a section of the upper wall closer to the rear of the vehicle is curved obliquely downwards so that the headwind that has flowed into the flow channel flows in the direction of the device for controlling exhaust emissions.

[0017] For example, under high-speed or high-speed driving conditions, the temperature of the exhaust emission control device is likely to increase because high-temperature exhaust gas is likely to flow into the device. Under such conditions, if the temperature of the exhaust emission control device exceeds the upper limit of the catalyst's activation temperature within the device, the catalyst's exhaust gas purification performance deteriorates.

[0018] To prevent a deterioration in the exhaust gas purification performance of the exhaust emission control device due to such high-temperature exhaust gas, a method for cooling the exhaust emission control device may be applicable. This method includes mixing unburned fuel into the exhaust gas, vaporizing the unburned fuel using the heat from the exhaust emission control device, and cooling the direct catalyst using the heat of vaporization. However, according to this method, fuel consumption increases by the amount of such unburned fuel mixed with the exhaust gas.

[0019] A section of the upper wall, closer to the rear of the vehicle, is curved downwards at an angle, directing the headwind flowing into the airflow channel formed in the space between the cylinder head-side heat insulation cover and the combustion engine towards the exhaust emission control device. This design allows the headwind flowing into the airflow channel to blow or flow against the exhaust emission control device. As a result, the headwind can cool the exhaust emission control device. Therefore, cooling of the unburned fuel as described above is unnecessary, or even if such cooling of the unburned fuel is carried out, the amount of unburned fuel to be mixed can be reduced. Consequently, the deterioration of the exhaust emission control device's performance can be prevented.In addition, an increase in fuel consumption due to the cooling of the exhaust emission control device can also be prevented.

[0020] In the thermal insulation structure of the internal combustion engine, in which the flow channel is formed in the space between the cylinder head-side thermal insulation cover and the internal combustion engine, it is preferred that an actively controllable radiator grille closure is arranged in a front part of the vehicle at a position that is closer to the front of the vehicle than an edge of the cylinder head-side thermal insulation cover is closer to the front of the vehicle, and controls a flow rate of the headwind that is introduced into the flow channel in the space between the cylinder head-side thermal insulation cover and the internal combustion engine.

[0021] This means that if the cylinder head temperature needs to rise, it is not preferable to allow backflow into the airflow channel while the vehicle is in motion. After the cylinder head temperature has risen, it is preferable to actively introduce backflow into the airflow channel in such a way that the cylinder head temperature rises excessively. Positioning the radiator grille closure closer to the front of the vehicle than the edge of the cylinder head-side heat insulation cover allows the amount of backflow introduced into the airflow channel to be adjusted according to the cylinder head cooling requirements. As a result, the appropriate cylinder head temperature can be maintained.

[0022] According to the invention, the thermal insulation structure of the internal combustion engine is provided in such a way that the cylinder head-side thermal insulation cover is vertically divided into an upper cylinder head-side thermal insulation cover and a lower cylinder head-side thermal insulation cover, wherein the upper cylinder head-side thermal insulation cover can be removed from the lower cylinder head-side thermal insulation cover, the upper cylinder head-side thermal insulation cover comprises the upper wall and upper sections of the first side walls, and the lower cylinder head-side thermal insulation cover comprises lower sections of the first side walls. Preferably, the lower cylinder head-side thermal insulation cover of the upper and lower cylinder head-side thermal insulation covers overlaps an upper section of the cylinder block-side thermal insulation cover when viewed from the side of the vehicle.

[0023] According to this design, the cylinder head-side heat insulation cover is vertically divided into the upper cylinder head-side heat insulation cover and the lower cylinder head-side heat insulation cover, with the upper cylinder head-side cover being removable from the lower cylinder head-side cover. Thus, the internal combustion engine becomes visible from above when the upper cylinder head-side cover is removed. If the upper and lower cylinder head-side covers are formed as a single piece, it is necessary to remove the entire cylinder head-side insulation cover from the vehicle body. However, if the upper cylinder head-side heat insulation cover is designed to be removable from the lower cylinder head-side heat insulation cover, the upper cylinder head-side heat insulation cover can be removed from the lower cylinder head-side heat insulation cover.As a result, the cover can be easily removed during maintenance of the combustion engine.

[0024] In the thermal insulation structure of the internal combustion engine, it is preferred that a congruent section of the first side wall of the cylinder head-side thermal insulation cover and the second side wall of the cylinder block-side thermal insulation cover has a vertical length that is set at 40 mm or more.

[0025] This means that the cylinder head-side cover cannot adequately insulate the cylinder head if the vertical length of the common or coinciding section of the first side wall of the cylinder head-side thermal insulation cover and the second side wall of the cylinder block-side thermal insulation cover is too short. Setting the vertical length of the coinciding section to 40 mm or more allows the cylinder head-side thermal insulation cover to adequately insulate the cylinder head. ADVANTAGES OF THE INVENTION

[0026] In light of the foregoing description, according to the heat-insulating structure of the internal combustion engine in the present disclosure, each of the first side walls is arranged outwards in the width direction of the vehicle or spaced apart from the corresponding second side wall, and the lower edge of each of the first side walls is arranged below the upper edge of the corresponding second side wall, so that it overlaps the corresponding second side wall when viewed from the side of the vehicle. Thus, the cylinder head can be kept warm and adequately cooled, while the cylinder block has a heat-insulating conductor. As a result, it becomes possible to cool a part of an internal combustion engine while the internal combustion engine as a whole is thermally insulated. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of an engine, which is an internal combustion engine with a thermal insulation structure according to an embodiment of the present disclosure. Fig. Figure 2 illustrates a condition in which a cover, viewed from above, covers the engine and a gearbox. Fig. Figure 3 illustrates the condition where, viewed from one side away from the gearbox, the cover covers the engine and gearbox. Fig. Figure 4 illustrates the condition in which the cover covers the engine and gearbox when viewed from a side adjacent to the gearbox. Fig. Figure 5 is a view showing an upper cylinder head-side heat insulation cover open, with the engine and transmission installed in a vehicle. Fig. Figure 6 is a diagram showing a relationship between the vertical length of a first side wall and the thermal insulation performance of the cylinder head. Fig. Figure 7 is a cross-sectional view of the front of the vehicle along a longitudinal direction of the vehicle in a state in which a bonnet and the upper cylinder head side cover are closed. Fig. Figure 8 illustrates a variation of the embodiment. DESCRIPTION OF THE EXECUTION FORMS

[0027] One embodiment of the present invention will now be described in detail with reference to the drawings.

[0028] Fig. Figure 1 is a cross-sectional view of a multi-cylinder engine (hereinafter referred to as "engine 1"), which comprises an internal combustion engine with a thermal insulation structure according to the embodiment. This engine 1 is mounted horizontally in an engine compartment at the front of the vehicle such that the direction of the cylinder bank coincides with the vehicle width direction (lateral direction in Fig. 1) In other words, engine 1 is a transversely mounted engine. Engine 1 is arranged such that its upper part is inclined towards the rear of the vehicle.

[0029] The engine 1 comprises a cylinder head 2, a cylinder block 3, and an oil pan 4, which are arranged vertically in that order and coupled together. In the following description, a side adjacent to the cylinder head 2 is referred to as the "upper side" or "top," and a side adjacent to the oil pan 4 is referred to as the "lower side" or "bottom."

[0030] In the upper section or part of the cylinder block 3, four cylinders 4 are arranged in a single row to form a cylinder bank. In the lower section of the cylinder block 3, a crankcase 7 is provided in which a crankshaft 6 is arranged.

[0031] A piston 8 is inserted into each of the cylinders 5 so that it can slide within the inner circumference of the respective cylinder 5. The piston 8 is connected to the crankshaft 6 by a connecting rod 9. A combustion chamber 10 is provided in each of the cylinders 5 (in Fig. 1 is only one shown), thus defined or limited by a top side of the piston 8, the inner wall surface of the cylinder 5 and the bottom side of the cylinder head 2.

[0032] The cylinder head 2 is provided for each cylinder 5 with an intake port (not shown) to introduce fresh air into the combustion chamber 10 and an exhaust port (not shown) to expel exhaust gas from the combustion chamber 10. The cylinder head 2 is also provided with an inlet (not shown) and an outlet (not shown) to allow the intake and exhaust ports to communicate with the combustion chamber 10. The cylinder head 2 is further provided with an intake valve (not shown) and an exhaust valve (not shown) configured to open / close the inlet and outlet, and is further equipped with a valve opening / closing mechanism (not shown) to open / close the intake and exhaust valves.

[0033] The cylinder head 2 is further equipped with a fuel injector 11 and a spark plug 12 for each cylinder 5 (in Fig. (Figure 1 shows only a valve and a spark plug). The fuel injector 11 injects fuel into the combustion chamber 10, and the spark plug 12 ignites the fuel injected into the combustion chamber 10 by the fuel injector 11.

[0034] A head cover 2a is attached to the top of the cylinder head 2.

[0035] The oil pan 4 stores oil, which is supplied, for example, to a bearing metal (not shown) of the crankshaft 6 and to a valve opening / closing mechanism, in particular a hydraulic opening / closing mechanism. Although not shown, an oil pump is arranged in the lower section of the cylinder block 3 to supply oil to each component of the engine 1.

[0036] A gearbox 20 is attached to one side of the engine 1 in the direction of the cylinder bank (left side of the vehicle (right side in Fig. 1) coupled in this embodiment. The engine 1 and the transmission 20 form a drive unit. The transmission 20 is an automatic transmission and has a transmission mechanism such as a torque converter (not shown) in a transmission housing. The transmission 20 is arranged horizontally, with input and output shafts, which are not shown, extending in the width direction of the vehicle. The input shaft is coupled to the crankshaft 6 of the engine 1, and the output shaft is coupled to a differential 23 (see Figure 1). Fig. 2 coupled), which is located in a section of the transmission 20 closer to the rear of the vehicle. Although not illustrated, left and right front wheel drive shafts, each coupled to the left and right front wheels respectively, extend from the differential 23 to both sides in the width direction of the vehicle.

[0037] As in Fig. Figure 2 shows an intake manifold 13 located on a section of the engine 1 closer to the front of the vehicle to introduce intake air into each cylinder 5 of the engine 1. This intake manifold 13 has four intake branch pipes, each belonging to one of the four cylinders 5 of the engine 1. The intake branch pipes are curved from an expansion tank that extends in the direction of the cylinder bank (the vehicle width direction) towards one end of the intake port, away from the combustion chamber 10. The intake branch pipes assigned to the respective cylinders 5 are connected to openings in the cylinder 5 intake manifolds, which open into side faces of the engine 1 closer to the front of the vehicle to communicate with the respective cylinders 5.

[0038] As in Fig. As shown in Figure 2, an exhaust manifold, covered or encased by a heat insulator 16, is provided on a part of the engine 1 closer to the rear of the vehicle to discharge exhaust gas from each of the cylinders 5 of the engine 1. The exhaust manifold has four exhaust branch pipes belonging to the four cylinders 5 of the engine 1, although the four exhaust branch pipes in Fig. 2 are not visible because they are covered by the thermal insulator 16. The four exhaust branch pipes transition into a compression pipe on the downstream side of a stream of exhaust air. The compression pipe is equipped with a direct catalyst 17, which functions as a device for controlling exhaust emissions and cleaning exhaust gas (see Figure 2). Fig. 17) The exhaust branch pipes belonging to the respective cylinders 5 are connected to openings in the exhaust ports of the cylinders 5 away from the combustion chamber 10, with the openings to side surfaces of the engine 1 being located closer to the rear of the vehicle to communicate with the respective cylinders 5. An upper section of the heat insulator 16 is provided with a plurality of openings 19 for introducing headwind into the heat insulator 16 during operation of the vehicle.

[0039] The engine 1 is provided with a heat insulation cover 30 adjacent to the cylinder head (hereinafter referred to as the "cylinder head-side heat insulation cover") and a heat insulation cover 40 adjacent to the cylinder block (hereinafter referred to as a "cylinder block-side heat insulation cover"). With reference to the Fig. 1-5 describe the designs of the respective thermal insulation covers 30 and 40.

[0040] The cylinder head-side thermal insulation cover 30 is a thermal insulation cover that covers the entire surface of the cylinder head 2, the entirety of both side faces of the cylinder head 2 in the width direction of the vehicle, and the upper sections of both side faces of the cylinder block 3 in the width direction of the vehicle. The cylinder block-side thermal insulation cover 40 is a thermal insulation cover that covers the entire cylinder block 3. Both the cylinder head-side thermal insulation cover 30 and the cylinder block-side thermal insulation cover 40 comprise a fibrous material, for example, glass wool, which possesses thermally insulating and sound-absorbing properties. This enables both the cylinder head-side thermal insulation cover 30 and the cylinder block-side thermal insulation cover 40 not only to thermally insulate the engine 1 but also, essentially, to prevent the release of engine noise to the outside of the vehicle.

[0041] The cylinder head-side thermal insulation cover 30 comprises an upper wall 31 and first side walls 32, as shown in Fig. Figure 1 illustrates. The upper wall 31 covers the entire top surface of the cylinder head 2. The first side walls 32 cover side surfaces of the cylinder head 2 in the vehicle width direction and upper sections of both side surfaces of the cylinder block 3 in the vehicle width direction.

[0042] The upper wall 31 faces the top of the cylinder head 2 (i.e., the top surface of the cylinder head cover 2a) and is spaced apart from it. Each of the first side walls 32 faces a corresponding side surface of the cylinder head 2 in the vehicle width direction and is spaced apart from it, and is also faced a corresponding side surface of the cylinder block 3 in the vehicle width direction and is spaced apart from it.

[0043] Each of the first side walls 32 is vertically divided into an upper side wall 32a and a lower side wall 32b. The upper side wall 32a covers an upper section of the corresponding side surface of the cylinder head 2 in the vehicle width direction. The lower side wall 32b covers the lower section of the corresponding side surface of the cylinder head 2 in the vehicle width direction and the upper section of the corresponding side surface of the cylinder block 3 in the vehicle width direction.

[0044] In other words, each of the first side walls 32 is vertically subdivided into an upper and a lower section. Thus, the cylinder head-side thermal insulation cover 30 is vertically subdivided into an upper cylinder head-side thermal insulation cover 33 and a lower thermal insulation cover 34. The upper cylinder head-side thermal insulation cover 33 comprises the upper wall 31 and the upper side wall 32a, which is the upper section of the first side wall 32 and is formed integrally with the upper wall 31. The lower cylinder head-side thermal insulation cover 34 comprises the lower side wall 32b, which is the lower section of the first side wall 32.

[0045] Both edges of the cylinder head-side thermal insulation cover 30 in the longitudinal direction of the vehicle are equipped with a release section 39 (see Fig. 5 and Fig. 7) provided where no wall is formed.

[0046] The upper wall 31 of the upper cylinder head-side thermal insulation cover 33 is covered, as shown in Fig. Figure 2 shows the entire top surface of the cylinder head 2 and the intake manifold 13. The length of the upper wall 31 in the vehicle width direction is lengthened or shortened according to the shape of the components connected to the cylinder 2.

[0047] Specifically, the section of the upper wall 31 closer to the front of the vehicle is provided with a radiator cover 60, which is attached to a front frame (not shown). The upper wall 31 extends with a predetermined length in the width direction of the vehicle from the position of the radiator cover 60 towards the rear of the vehicle, and extends outwards in the width direction of the vehicle to bypass the right side face of the cylinder head 2 (in the width direction of the vehicle) and the expansion tank.The upper wall 31 further extends towards the end of the cylinder head 2 closer to the rear of the vehicle with its extended length in the vehicle width direction, and both sides of the upper wall 31 in the vehicle width direction are shortened inwards in the vehicle width direction to achieve a position near an instrument panel 61 located in a section of the upper cylinder head-side thermal insulation cover 33 closer to the rear of the vehicle. Likewise, as in . Fig. As illustrated in Figure 2, recesses 31b are formed at positions near both ends in the vehicle width direction, and on the upper wall 31 at the edge closer to the rear of the vehicle. The recesses 31b are cut upwards to allow a hinge mechanism 36, which will be described later, to open / close the upper cylinder head-side thermal insulation cover 33.

[0048] As in the Fig. 3 and Fig. As shown in Figure 4, the upper wall 31 extends obliquely upwards from the location of the radiator cover 60, viewed from the side of the vehicle, towards the rear of the vehicle. The upper wall 31 is then bent obliquely downwards from a position corresponding to an end of the exhaust manifold on the upstream side of the exhaust air flow (a connecting section between the exhaust manifold and the outlet) in the longitudinal direction of the vehicle, reaching a position not far from the dashboard 61. The curved shape of the upper wall 31 closer to the rear of the vehicle is suitably adjusted such that the headwind coming from the opening 39a (see Figure 4) Fig. 5) is introduced into the cylinder head-side insulation cover 30 at the front of the vehicle, flowing towards the direct catalyst 17 (see Fig. 7), which is connected to one end of the exhaust manifold on the downstream side of the exhaust air stream.

[0049] Furthermore, as in the Fig. 3 and Fig. As illustrated in Figure 4, the edge of the upper wall 31, closer to the front of the vehicle, projects beyond the edge of the upper side wall 32a, also closer to the front of the vehicle. This projection (hereinafter referred to as projection 31a'') is mounted on the front support or bearing 35.

[0050] As in Fig. Figure 1 shows the upper side wall 32a of the upper cylinder head-side thermal insulation cover 33 having its upper edge formed integrally with both edges of the upper wall 31 in the vehicle width direction. The upper side wall 32a is therefore formed integrally with the upper wall 31 and extends substantially vertically downwards from the section formed integrally with the upper wall 31.

[0051] Likewise, as in Fig. As shown in Figure 4, the upper side wall 32a has a downwardly open recess on the left side in the vehicle width direction, in a section corresponding to the expansion tank. This recess and a recess formed in the lower side wall 32b create a through-opening 30a. This through-opening 30a is provided to allow, for example, an intake pipe to extend outside the cylinder head-side thermal insulation cover 30. Although not shown, the through-opening 30a is sealed after expansion, for example of the intake pipe, with a damping material such as urethane, which has thermally insulating properties.

[0052] The upper cylinder head-side thermal insulation cover 32a is supported by the vehicle body elements near the front and rear of the vehicle, as shown in the Fig. Figures 2-4 illustrate how the vehicle body elements support the upper cylinder head-side heat insulation cover 33. A more detailed description follows.

[0053] As in Fig. As shown in Figure 2, the top of the radiator cover 60 is provided with the front support 35, which positions the section of the upper cylinder head-side heat insulation cover 33 closer to the front of the vehicle. The front support 35 is attached to the radiator cover 60. As described above, the radiator cover 60 is attached to the front frame, which forms the vehicle body elements. Thus, the front support 35 is supported by the vehicle body elements through the radiator cover 60. As shown in the Fig. 3 and Fig. As shown in Figure 4, a step 35a is formed in a section of the front support 35 closer to the rear of the vehicle. The projection 31a of the upper wall 31 described above is mounted on the step 35a. This allows the front support 35 to support or bear the section of the upper cylinder head-side thermal insulation cover 33 closer to the front of the vehicle. The top of the front support 35 is tilted upwards, towards the rear of the vehicle, to be continuous with the shape of the top of the upper wall 31 with the projection 31a mounted on the step 35a.

[0054] As in the Fig. 3 and Fig. As illustrated in Figure 4, a space 62 exists between the radiator cover 60 and the edge of the upper side wall 32a closer to the front of the vehicle, adjacent to the upper cylinder head-side thermal insulation cover 33 with the projection 31a mounted to the step 35a of the front support 35. This space 62 prevents contact between the edge of the upper side wall 32a closer to the front of the vehicle (specifically, the lower edge of the upper side wall 32a closer to the front of the vehicle) and the radiator cover 60 when the upper cylinder head-side thermal insulation cover 33 is rotated upwards by a hinge mechanism 46, which will be described later.

[0055] The section of the upper cylinder head-side thermal insulation cover 33 closer to the rear of the vehicle is provided with hinge mechanisms 36 that serve as a rear support for holding the upper cylinder head-side thermal insulation cover 33 closer to the rear of the vehicle. As shown in Fig. As shown in Figure 2, the hinge mechanisms 36 are provided on both sides of the section of the upper cylinder head-side thermal insulation cover 33 closer to the rear of the vehicle in the vehicle width direction. Each of the hinge mechanisms 36 comprises, as shown in the Fig. 3 and Fig. Figure 4 shows a bracket 36a and a pin 36b. The bracket 36a is attached to the instrument panel 61, which is part of the vehicle body. The pin 36b is attached to the bracket 36a. Specifically, a section of each bracket 36a closer to the rear of the vehicle is attached to the instrument panel 61, for example, with a bolt, and extends longitudinally from the attached section toward the front of the vehicle. The pin 36b is attached to a section of the bracket 36a closer to the front of the vehicle such that it projects outward from the bracket 36a in the vehicle's width direction. The outwardly projecting section of the pin 36b is inserted through the edge of the upper side wall 32 closer to the rear of the vehicle of the upper cylinder head-side cover 33. This allows the upper cylinder head-side cover 33 to be rotated vertically with the pin 36b as a pivot point.If the pin 36b is inserted through the edge of the upper side wall 32a closer to the rear of the vehicle, the section of the upper cylinder head-side cover 33 closer to the rear of the vehicle is mounted on the dashboard 61, i.e., the vehicle body element, by the hinge mechanism 36. In other words, the hinge mechanism 36 mounts the cylinder head-side thermal insulation cover 30, specifically the upper cylinder head-side thermal insulation cover 33, in a rotatable manner.

[0056] The upper cylinder head-side cover 30 is vertically divided into the upper cylinder head-side thermal insulation cover 33 and the lower cylinder head-side thermal insulation cover 34, and the upper cylinder head-side thermal insulation cover 33 is mounted vertically rotatably by the hinge mechanism 36. This allows the cylinder head-side thermal insulation cover 33 to rotate with the pin 36a of the hinge mechanism 36 as its pivot point between a closed position of the cylinder head-side thermal insulation cover 30, in which the motor 1 is covered and shielded from above, and an open position, in which the motor 1 is visible from above.

[0057] As in Fig. As shown in Figure 5, when the upper cylinder head-side heat insulation cover 33 is rotated upwards with the pin 36a as its pivot point, the upper cylinder head-side heat insulation cover 33 is positioned in the open position, where the motor 1 is visible from above. Conversely, when the upper cylinder head-side heat insulation cover 33 is rotated downwards from the open position, it is positioned in the closed position, where the motor 1 is covered and shielded from above, as indicated by the imaginary line in Figure 5. Fig. 5 illustrates.

[0058] As in Fig. As illustrated in Figure 1, each lower cylinder head-side thermal insulation cover 34 is arranged outwards in the vehicle width direction relative to the upper cylinder head-side thermal insulation cover 33. The upper edge of the lower cylinder head-side thermal insulation cover 34, i.e., the upper edge of the lower side wall 32b, is provided with a rubber element 37 that extends over the entire upper edge in the longitudinal direction of the vehicle. The upper cylinder head-side thermal insulation cover 33 (more precisely, the upper side wall 32a of the upper cylinder head-side thermal insulation cover 33) is designed to abut the rubber element 37 in the lower cylinder head-side thermal insulation cover 34 (i.e., the lower side wall 32b) from the side of the vehicle when in the closed position.As a result, no gap is formed between the lower edge of the upper cylinder head-side heat insulation cover 33 and the lower edge of the cylinder head-side heat insulation cover 34, more precisely between the upper side wall 32a and the lower side wall 32b along the longitudinal direction of the vehicle. This prevents a deterioration of the heat insulation properties of the cylinder head-side heat insulation cover 30 due to the division of the cylinder head-side heat insulation cover 30 into the upper cylinder head-side heat insulation cover 33 and the lower cylinder head-side heat insulation cover 34.

[0059] The length of the lower cylinder head-side thermal insulation cover 34 in the longitudinal direction of the vehicle is shorter than that of the upper side wall 32a in the longitudinal direction of the vehicle, as shown in the Fig. 3 and Fig. Figure 4 shows this. Specifically, the edge of the lower cylinder head-side thermal insulation cover 34, closer to the front of the vehicle, is positioned in essentially the same location as the upper side wall 32a, also closer to the front of the vehicle. The edge of the lower cylinder head-side thermal insulation cover 34, closer to the rear of the vehicle, is located closer to the front of the vehicle than the edge of the upper side wall 32a, which is also closer to the rear of the vehicle, in the longitudinal direction of the vehicle. As a result, there is a space behind the edge of the lower cylinder head-side thermal insulation cover 34, closer to the rear of the vehicle, i.e., below the section of the upper cylinder head-side thermal insulation cover 33, closer to the rear of the vehicle, more precisely below the section of the upper cylinder head-side thermal insulation cover 33 where the hinge mechanism 36 is located.As a result, when the upper cylinder head-side thermal insulation cover 33 is rotated between the closed and open positions by the hinge mechanism 36, such a space is used to allow the upper cylinder head-side thermal insulation cover 33 to be rotated close to the hinge mechanism 36.

[0060] In contrast, the vertical length of the lower cylinder head-side thermal insulation cover 34 is long enough to provide sufficient thermal insulation for the cylinder head 2. Specifically, the lower edge of the lower side wall 32b, which is the lower cylinder head-side thermal insulation cover 34, is positioned below an upper edge of a corresponding second side wall 43. Thus, a predetermined length or more of the lower side wall 32b overlaps the corresponding second side wall 43 when viewed from the side of the vehicle.

[0061] This means that heat from the cylinder head 2 and cylinder block 3 is dissipated to the air via heat transfer and radiation after the engine 1 has been stopped. The air around the cylinder head 2 and cylinder block 3, heated by heat transfer from these two bodies, rises and remains within the cylinder head-side heat insulation cover 30. By allowing the lower edge of the first side wall 32b of the lower cylinder head-side heat insulation cover 34 to be positioned below the upper edge of the second side wall 43, the volume of air contained within the cylinder head-side heat insulation cover 30 (more precisely, the lower side wall 32b of the lower cylinder head-side heat insulation cover 34) can increase. Therefore, the cylinder head 2 can be covered with a large volume of heated air, effectively insulating the cylinder head 2.Furthermore, the first side wall 32 (more precisely, the lower side wall 32b) and the second side wall 43 overlap each other when viewed from the side of the vehicle. The overlapping section can doubly shield the radiation from the cylinder block 3, and thus the heat from the cylinder block 3 can also be effectively insulated.

[0062] The vertical length of the lower cylinder head-side insulation cover 34 is now described, more precisely with reference to Fig. 6.

[0063] Fig. Figure 6 is a diagram showing the calculated result of a relationship between the vertical length of the first side wall 32 (i.e., the total vertical length of the upper side wall 32a and the vertical length of the lower side wall 32b) and the heat-insulating state of the cylinder head 2. This relationship is calculated by a simulation. Fig. 6 the abscissa represents the vertical length of the first side wall 32, whereas the ordinate represents the temperature of the cylinder head 2 after one hour has elapsed since the engine 1 was stopped, which was operated to raise the temperature of the cylinder head 2 (hereinafter referred to as "temperature after one hour").

[0064] In this simulation, the calculation is performed using a model in which the first side wall 32 is not divided into the upper side wall 32a and the lower side wall 32b, and in which the upper side wall 32a and the lower side wall 32b are formed integrally. In this embodiment, when the upper cylinder head-side thermal insulation cover 33 is in the closed position, the upper cylinder head-side thermal insulation cover 33 rests against the rubber element 37 provided in the lower thermal insulation cover 34 to prevent a gap from forming between the upper side wall 32a and the lower side wall 32b, such that the upper side wall 32a and the lower side wall 32b are formed almost integrally. The configuration of the above model has the same thermal insulation performance as this embodiment. Fig. In section 6, it is assumed that the distance between the upper wall 31 and the top of the cylinder head 2 is 100 mm, and that the vertical length of the cylinder head 2 is 180 mm. This means that in this simulation, if the vertical length of the first side wall 32 is 100 mm, the height of the lower edge of the first side wall 32 will be the same as that of the top of the cylinder head 2. If the vertical length of the first side wall 32 is 280 mm, the height of the lower edge of the first side wall 32 will be the same as that of the bottom surface of the cylinder head 2. This simulation also calculates the temperature of the cylinder head 2 after one hour has passed since the engine 1, which was running to raise the temperature to 90°C, was stopped. The ambient air temperature is assumed to be 25°C.

[0065] With reference to Fig. 6. If the vertical length of the first side wall 32 is 100 mm, i.e., if the height of the top of the cylinder head 2 is the same as that of the lower edge of the first side wall 32, and the side surface of the cylinder head 2 is not covered by the first side wall 32 in the vehicle width direction, the temperature drops to 71°C after one hour. If the vertical length of the lower side wall 32 increases from this length, the temperature rises after one hour with the increase in the vertical length of the first side wall 32. If the vertical length of the first side wall 32 is approximately 280 mm, i.e., if the height of the bottom surface of the cylinder head 2 is the same as that of the lower edge of the first side wall 32, the temperature reaches 83°C after one hour.This means that even if the vertical position of the bottom surface of the cylinder head 2 is the same as that of the lower edge of the first side wall 32, the temperature drops by approximately 10 °C after one hour. In a situation where the vertical length of the entire lower side wall 32 continues to increase to allow the lower section of the first side wall 32 to overlap with the side surface of the cylinder block 3 in the width direction of the vehicle, when the vertical length of the first side wall 32 is approximately 320 mm, the temperature reaches 85 °C after one hour. If the vertical length of the first side wall 32 continues to increase beyond this point, the temperature rises slightly after one hour.

[0066] This means that, according to this simulation, in order to maintain the temperature of the cylinder head 2 at 85°C or higher after one hour, the vertical length of the first side wall 32 must be long enough to allow its lower edge to overlap with the side surface of the cylinder block 3 in the vehicle width direction. Specifically, it is assumed that the overlapping section of the first side wall 32 and the side surface of the cylinder block 3 in the vehicle width direction is calculated such that the temperature is 85°C or higher after one hour. If the temperature is 85°C or higher after one hour, the vertical length of the first side wall 32 is 320 mm. Thus, the overlapping section is 40 mm, which is a result of subtracting the distance between the upper wall 31 and the top of the cylinder head 2 (100 mm) and the vertical length of the cylinder head 2 (180 mm).In other words, the overlap section of the first side wall 32 and the side surface of the cylinder block 3 should have a length of 40 mm or more in the vehicle width direction so that the temperature reaches 85 °C or more after one hour. At this length, the vertical length of the lower side wall 32b, i.e., the vertical length of the lower cylinder head-side thermal insulation cover 34, is determined such that the overlapping section of the lower cylinder head-side thermal insulation cover 34 with the side surface of the cylinder block 3 in the vehicle width direction, more precisely the second side wall 43 of the cylinder block-side thermal insulation cover 40, which covers the cylinder block 3, has a length of approximately 40 mm or more when viewed from the side of the vehicle.

[0067] The lower cylinder head-side heat insulation cover 34 on the right side in the vehicle width direction is attached to a door frame (not shown), whereas the lower cylinder head-side heat insulation cover 34 on the left side in the vehicle width direction is attached to a battery bracket (not shown).

[0068] The cylinder head-side thermal insulation cover 40 comprises, as shown in Fig. Figure 3 shows a front wall 41, a rear wall 42, the second side walls 43, and a bottom 44. The front wall 41 covers a surface of the cylinder block 3 closer to the front of the vehicle. The rear wall 42 covers a surface of the cylinder block 3 closer to the rear of the vehicle. The second side walls 43 cover both sides of the cylinder block 3 in the direction of the vehicle's width. The bottom 44 essentially covers the entire oil pan 4.

[0069] Elements 41-44 of the cylinder block-side thermal insulation cover 40 are arranged in the vehicle width direction within the cylinder head-side thermal insulation cover 30. Specifically, elements 41-44 are arranged such that they contact the surfaces of the cylinder block 3 and the oil pan 4. In particular, they contact, as shown in Fig. Figure 3 illustrates that elements 41 to 44 cover the surfaces of the cylinder block 3 and the oil pan 4, while simultaneously avoiding contact with auxiliary machinery, including a water pump (not shown), an alternator (not shown), an air compressor (not shown), and a timing chain sprocket 18 on the cylinder block 3, and a connection between the transmission 20 and the engine 1, as shown in Fig. 1 shown.

[0070] The front wall 41, the rear wall 42, and the second side walls 43 of the cylinder block-side thermal insulation cover 40 extend towards the upper edges of the respective side faces of the cylinder block 3 to cover the respective side face. As shown in Fig. As shown in Figure 3, this allows the lower section of the first side wall 32 of the cylinder head-side heat insulation cover 30, in particular the lower section of the lower cylinder head-side heat insulation cover 34, to overlap vertically with the upper section of the second side wall 43 of the cylinder block-side heat insulation cover 40 when viewed from the side of the vehicle.

[0071] Although not shown, the cylinder block-side thermal insulation cover 40 is screwed to brackets provided on the side surfaces of the cylinder block 3 and the oil pan 4 for attachment to the cylinder block 3 and the oil pan 4.

[0072] As in Fig. As shown in Figure 4, in this embodiment the gearbox 4 is also provided with a cover for thermal insulation of the gearbox 20 (hereinafter referred to as a "heat-insulating gearbox cover 50").

[0073] Similar to the cylinder block-side heat insulation cover 40, the gearbox heat insulation cover 50 is arranged in such a way that it touches the entire surface of the gearbox 20 in order to avoid contact with, for example, auxiliary or secondary machines connected to the gearbox 20.

[0074] The gearbox heat insulation cover 50 is attached to the gearbox 20, for example with a bolt, as shown in Fig. 4 shown.

[0075] In this way, the transmission 20 is covered with the transmission heat insulation cover 50 to provide thermal insulation. This reduces the viscosity of the lubricating oil supplied to, for example, a torque converter of the transmission 20. This makes it possible to supply the required amount of lubricating oil for lubricating, for example, the torque converter, even if the drive force of the oil pump located in the transmission 20, which is driven by the engine 1 and supplies the torque converter with lubricating oil, decreases. As a result, the engine power required to generate the drive force for the oil pump can be reduced to improve fuel efficiency. If the transmission 20 is a manual transmission, it is necessary to cool the transmission itself against the airflow entering the vehicle while it is in motion, and therefore the transmission heat insulation cover 50 is not required.

[0076] Next, with reference to Fig. 7 a radiator grille closure 70 for adjusting the amount of headwind penetrating the cylinder head-side heat insulation cover 30 while the vehicle is in motion is described. In Fig. Figure 7 only illustrates the outline of the cylinder head 2 and the cylinder block 3, and the depiction of the internal design is omitted.

[0077] As in Fig. Figure 7 illustrates that the radiator grille closure 70 is located in front of the edge of the cylinder head-side heat insulation cover 30, closer to the front of the vehicle in the longitudinal direction of the vehicle, more precisely in front of the radiator cover 60 in the longitudinal direction of the vehicle. The radiator grille closure 70 comprises a plurality of vertically rotatable ribs 71 (five ribs in Fig. 7), which are arranged in a vertical direction, and a rotation of the ribs 71 adjusts the degree of opening of the radiator grille closure 70. Specifically, the radiator grille closure 70 is configured such that the degree of opening of the radiator grille closure 70 is minimal in a situation where the orientation of the ribs 71 is perpendicular to the direction of travel of the vehicle, whereas the degree of opening of the radiator grille closure 70 is increased in a situation where the ribs 71 are rotated (rotated counterclockwise). Fig. 7), is at its maximum to allow the ribs 71 to be aligned parallel to the vehicle's direction of travel. The amount of headwind penetrating the cylinder head-side heat insulation cover 30 while the vehicle is in motion is set to increase with the degree of opening of the radiator grille closure 70.

[0078] The rotation angle of each rib 71 (i.e., the degree of opening of the radiator grille closure 70) is configured to be changed by a control signal from a control unit (not shown). When cooling of the engine 1, particularly the cylinder head 2, is required, the control unit adjusts the amount of headwind entering the cylinder head-side heat insulation cover 30 during vehicle operation by adjusting the angle of each rib 71 as needed. Specifically, the control unit detects the temperature of the engine coolant (hereinafter referred to as the engine coolant temperature) based on a signal from a water temperature sensor (not shown) inserted into a water jacket (not shown) of the cylinder head 2, and estimates the exhaust gas temperature based on engine torque or the amount of fresh air introduced.The control unit first acquires a characteristic map to determine the rotation angle of each fin 71 based on the detected engine water temperature and the estimated exhaust gas temperature. The control unit determines the rotation angle of each fin 71 based on this characteristic map. As a result, the appropriate amount of airflow enters the vehicle while driving, as required to cool the cylinder head 2. The control unit can be configured to estimate the temperature of the cylinder head 2 based on the detected water temperature and the estimated exhaust gas temperature, in order to determine the rotation angle of each fin 71 based on this estimated temperature.

[0079] Maintaining the temperature of the engine 1 by means of the cylinder head-side and cylinder block-side thermal insulation covers 30 and 40 enables rapid warm-up of the engine 1 in situations where the engine 1 is restarted after a temporary stop or when the engine 1 is started from a cold state. In particular, in this embodiment, viewed from the side of the vehicle, the vertical length of the first side wall 32 (strictly speaking, the lower side wall 32b) is such that the lower section of the first side wall 32 overlaps the side surface of the cylinder block 3 in the vehicle width direction, i.e., the upper section of the second side wall 43. Thus, sufficient thermal insulation can be achieved. In this way, if the engine 1 can be warmed up quickly, it is possible to reduce the amount of exhaust gas during engine 1 start-up.

[0080] Under high-speed conditions, heat becomes trapped in the cylinder block-side heat insulation cover 20 and the cylinder head-side heat insulation cover 40, leading to an excessively high temperature of the cylinder head 2. A fuel injector 11 and a spark plug 2, located on the cylinder head 2, have a relatively low thermal resistance. Therefore, it is necessary to cool the cylinder head 2 to prevent malfunctions of these components. It is not desirable for the cylinder block 3 to be cooled as much as the cylinder head 2 in order to maintain a suitable temperature of the inner cylinder.

[0081] In this embodiment, the cylinder head-side heat insulation cover 30 is provided separately from the top of the cylinder head 2 and both side surfaces of the cylinder block 3 in the vehicle width direction. Thus, headwind penetrating through the radiator grille closure 70 from the front of the vehicle while the vehicle is running is prevented from entering the release section 39a (see figure). Fig. 5) The airflow is directed from the cylinder head-side heat insulation cover 30 at the front of the vehicle into a space between the cylinder head-side heat insulation cover 30 and the engine 1 (the cylinder head 2 and the cylinder block 3) and flows through a space between the cylinder head-side heat insulation cover 30 and the cylinder head 2 and the cylinder head 3 to cool the cylinder head 2. In other words, a space between the cylinder head-side heat insulation cover 30 and the engine 1 forms a flow channel through which the airflow passes.

[0082] The cylinder block-side thermal insulation cover 40 is positioned on the cylinder block 3 to contact its surfaces: the surface closer to the front of the vehicle, the surface closer to the rear, and the two side surfaces in the vehicle's width direction. This prevents the headwind from coming into direct contact with the cylinder block 3 during vehicle operation, thus preventing the cylinder block 3 from being cooled by the headwind. This means the cylinder block 3 can be kept warm while being actively cooled.

[0083] Furthermore, in this embodiment, the radiator grille closure 70 can adjust the amount of headwind flowing into the flow channel in the space between the cylinder head-side heat insulation cover 30 and the engine 1 (flowing into cylinder head 2 and cylinder head 3) while the vehicle is in motion. This makes it possible to limit the amount of airflow while the vehicle is in motion, so that an unnecessarily large amount of headwind is not introduced to cool cylinder head 2.

[0084] Therefore, according to this embodiment, the cylinder block 2, which is part of the engine 1, can be actively cooled, while the engine 1 as a whole can be kept warm.

[0085] In this embodiment, the section of the upper wall 31 closer to the rear of the vehicle is bent downwards at such an angle that the headwind, which is introduced into the flow channel in the space between the cylinder head-side heat insulation cover 30 and the engine 1 (the cylinder block 2 and the cylinder head 3) while the vehicle is in motion, flows towards the exhaust manifold and the direct catalyst 17. This can prevent a deterioration in the exhaust gas purification performance of the direct catalyst 17 when high-temperature exhaust gas is expelled under high-speed conditions. Furthermore, this can prevent a deterioration in fuel consumption due to the cooling of the direct catalyst 17.

[0086] This means that under high-speed driving conditions, since the high-temperature exhaust gas is likely to flow into the direct catalyst 17, the temperature of the direct catalyst 17 is likely to increase. The exhaust gas purification performance of the direct catalyst 17 is improved by the increase in the temperature of a catalyst within the direct catalyst 17 and the activation of the catalyst. However, if the temperature of the catalyst within the direct catalyst 17 exceeds the maximum activation temperature, the exhaust gas purification performance of the catalyst deteriorates.

[0087] To prevent a significant deterioration in the exhaust gas purification performance of the direct catalyst 17 (more precisely, of the catalyst within the direct catalyst 17), a method for cooling the direct catalyst 17 can be employed. This method comprises mixing unburned fuel with the exhaust gas, vaporizing the unburned fuel using the heat from the direct catalyst 17 (more precisely, the catalyst within the direct catalyst 17), and cooling the direct catalyst 17 using the heat of vaporization. However, according to this method, the fuel consumption of such unburned fuel mixed with the exhaust gas increases.

[0088] In this embodiment, the section of the upper wall 31 closer to the rear of the vehicle is bent obliquely downwards, so that the headwind, while the vehicle is moving, flows towards the exhaust manifold and the direct catalyst 17. Accordingly, as shown in Fig. The 7 empty arrows shown represent the airflow while the vehicle is moving, from release section 39a (see below). Fig. 5) The airflow is directed into the cylinder head-side heat insulation cover 30 closer to the front of the vehicle and then flows through the space between the cylinder head 2 and the cylinder head-side heat insulation cover 30 towards the rear of the vehicle. The direction of the airflow in the curved section of the upper wall 31 closer to the rear of the vehicle changes such that the headwind flows towards the exhaust manifold and the direct catalyst 17. Thus, the headwind is directed out of a release section 39b of the cylinder head-side heat insulation cover 30 closer to the rear of the vehicle to flow towards the exhaust manifold and the direct catalyst 17. As described above, the top of a heat insulator 16 covering the exhaust manifold and the direct catalyst 17 is provided with a plurality of openings 19 (see Figure 1). Fig. 2) which allow the headwind to flow into the heat insulator 16 while the vehicle is in motion. Thus, the airflow from the opening 19 into the heat insulator 16 can cool the direct catalyst 17. This can essentially not only prevent the deterioration of the exhaust gas purification performance of the direct catalyst 17, but also an increase in fuel consumption due to the cooling of the direct catalyst 17.

[0089] Furthermore, in this embodiment, the upper cylinder head-side heat insulation cover 33 of the cylinder head-side heat insulation cover 30 is provided with hinge mechanisms 36 that are capable of opening / closing the upper cylinder head-side heat insulation cover 33. Thus, for example, oil in the engine 1 can be turned into the open position with the upper cylinder head-side heat insulation cover 33. This can simplify the maintenance of the engine 1, even when the cylinder head 2 is covered from above by the cylinder head-side heat insulation cover 30.

[0090] Fig. Figure 8 illustrates a variation of the embodiment. Specifically, in the embodiment above, the upper side wall 32a of the upper cylinder head-side thermal insulation cover 33 is provided with the hinge mechanism 36 to open / close the entire upper cylinder head-side thermal insulation cover 33. Alternatively, as shown in Fig. Figure 8 illustrates that, instead of providing the upper side wall 32a with the hinge mechanism 36, substantially the entire upper wall 31 is recessed to form a cover 38, and the cover 38 can be provided with hinge mechanisms 136. In such an embodiment, the hinge mechanism 136 rotates the cover 38 upwards to open it, thereby allowing the engine 1 to be viewed from above. Such an embodiment can also simplify the maintenance of the engine 1, even when the cylinder head 2 is fitted with the cylinder head-side thermal insulation cover 30.

[0091] In the above embodiment, a space is also required to prevent contact between the edge of the upper side wall 32a, closer to the front of the vehicle, and the radiator cover 60 when the upper cylinder head-side heat insulation cover 33 is rotated by the hinge mechanism 36. In this variation, the cover 38 does not rest against the radiator cover 60, and therefore no space is required, which is an advantage of this variant.

[0092] In this variant, the hinge mechanism 136 can, for example, be located on an edge of the cover 38 in the width direction of the vehicle or on an edge of the cover 28 closer to the front of the vehicle, as long as the cover 38 can be opened / closed. A hood 80 is provided above the cylinder head-side heat insulation cover 30. To limit the rotation range of the cover 38 as described in Fig.To enlarge the area shown in Figure 8, it is preferred to place the hinge mechanism 136 on the edge of the cover 38 closer to the rear of the vehicle.

[0093] The present disclosure is not limited to this embodiment. Any reasonable modification may be made within the scope of protection of the claims.

[0094] For example, in the embodiment above, the cylinder head-side thermal insulation cover 30 is divided into the upper and lower cylinder head-side thermal insulation covers 33 and 34. However, this is only one example of the present disclosure. The upper and lower thermal insulation covers 33 and 34 can be formed integrally with each other.

[0095] In the embodiment described above, the second side walls 43 of the cylinder block-side thermal insulation cover 40 contact the two side surfaces of the cylinder block 3 in the vehicle width direction. However, this is merely an example of the present disclosure. As long as the second side walls 43 are provided within the first side walls 32 in the vehicle width direction, a gap can be formed between each of the second side walls 43 and the corresponding side surfaces of the cylinder block 3 in the vehicle width direction.The distance between each of the second side walls 43 and the corresponding side surfaces of the cylinder block 3 in the vehicle width direction is narrower than a distance between each of the first side walls 32 and the corresponding side surfaces of the cylinder head 2 in the vehicle width direction, and a distance between each of the first side walls 32 and the corresponding side surfaces of the cylinder block 3 in the vehicle width direction.

[0096] Furthermore, in the above embodiment, the cylinder head-side heat insulation cover 30 (strictly speaking, the upper cylinder head-side heat insulation cover 33) is provided with the hinge mechanisms 36 (136). Alternatively, the hinge mechanisms 36 (136) need not be provided. In this case, during maintenance of the engine 1, the entire cylinder head-side heat insulation cover 30 must be removed from the vehicle body, or the upper cylinder head-side heat insulation cover 33 must be removed from the lower cylinder head-side heat insulation cover 34, or the cover 38 must be removed from the upper wall 31.

[0097] The above embodiment is aimed at a transversely mounted engine. However, this is merely one example of the present disclosure. The thermal insulation structure according to the embodiment can be applied to an engine with vertical cylinders, in which the direction of the cylinder bank coincides with the longitudinal direction of the vehicle, and to a V-engine in which the cylinders are arranged to form a V-shape.

[0098] The aforementioned embodiment is merely exemplary and preferred, and the scope of protection of this disclosure is not to be interpreted as limiting. The scope of protection of the invention is defined by the appended claims, and all variants and modifications that fall within the scope of protection of the present disclosure are also within the scope of protection of this disclosure. INDUSTRIAL APPLICABILITY

[0099] The present disclosure is useful as a thermal insulation structure for an internal combustion engine accommodated in an engine compartment provided in the front of a vehicle and opened / closed by a hood, comprising a cylinder block and a cylinder head coupled to the top of the cylinder block. REFERENCE MARK LIST 1 Engine (internal combustion engine) 2 cylinder heads 3-cylinder block 17 Direct catalyst (exhaust gas purification device) 30 Cylinder head side heat insulation cover 31 upper wall 32 first side wall 33 Upper cylinder head side heat insulation cover 34 lower cylinder head side heat insulation cover 36 hinge mechanism 38 lids 39 Release section 40 Cylinder block-side thermal insulation cover 41 front wall 42 rear wall 43 second side wall 70 Radiator grille lock 136 Hinge mechanism

Claims

[1] Thermal insulation structure for an internal combustion engine (1) which is accommodated in an engine compartment provided on the front of a vehicle and is opened / closed by an engine hood (80) and which comprises a cylinder block (3) and a cylinder head (2) coupled to a top of the cylinder block (3), having the thermal insulation structure: a cylinder head-side thermal insulation cover (30), comprising an upper wall (31) which faces and is spaced apart from the top surface of the cylinder head (2) and which covers an entire top surface of the head, first side walls (32) extending in a longitudinal direction of the vehicle and each facing and spaced apart from a corresponding one of the two side surfaces of the cylinder head (2) in a transverse direction of the vehicle and a corresponding one of the upper sections of both side surfaces of the cylinder block (3) in the transverse direction of the vehicle, and each covering the corresponding one of the two side surfaces of the cylinder head (2) in the transverse direction of the vehicle and the corresponding one of the upper sections of the two side surfaces of the cylinder block (3) in the transverse direction of the vehicle, and Release sections (39) formed at each of the two edges of the cylinder head-side thermal insulation cover (30) in a longitudinal direction of the vehicle; and a cylinder block-side thermal insulation cover (40), comprising a front wall (41) covering a front surface of the cylinder block (3), a rear wall (42) covering a rear surface of the cylinder block (3), and second side walls (43) each covering a corresponding side surface of the cylinder block (3) in the width direction of the vehicle, wherein Each of the first side walls (32) is arranged outwards in the width direction of the vehicle and spaced apart from a corresponding second side wall (43), and a lower edge of each of the first side walls (32) is positioned below an upper edge of the corresponding second side wall (43) so that it overlaps the corresponding second side wall (43) when viewed from one side of the vehicle, characterized by , that the cylinder head-side thermal insulation cover (30) is vertically divided into an upper cylinder head-side thermal insulation cover (33) and a lower cylinder head-side thermal insulation cover (34), wherein the upper cylinder head-side thermal insulation cover (33) can be removed from the lower cylinder head-side thermal insulation cover (34), the upper cylinder head-side thermal insulation cover (33) includes the upper wall (31) and upper sections of the first side walls (32) and the lower cylinder head-side thermal insulation cover (34) includes lower sections of the first side walls (32). [2] Thermal insulation structure of the internal combustion engine (1) according to claim 1, wherein where the front wall (41) of the cylinder block-side thermal insulation cover (40) touches the front surface of the cylinder block (3), the rear wall (42) touches the rear surface of the cylinder block (3), and Each of the second side walls (43) touches the corresponding of the two side surfaces of the cylinder block (3) in the width direction of the vehicle. [3] Thermal insulation structure of the internal combustion engine (1) according to claim 1 or 2, wherein a device for controlling exhaust emissions (17) in the longitudinal direction of the vehicle is arranged behind the internal combustion engine (1), and below an edge of the upper wall (31), a space between the cylinder head-side heat insulation cover (30) and the internal combustion engine (1) forms a flow channel into which, during operation of the vehicle, headwind flows from the release section (39) and is discharged from the release section (39), and a section of the upper wall (31) is curved obliquely downwards, so that the headwind which has flowed into the flow channel flows towards the device for controlling exhaust emissions (17). [4] Thermal insulation structure of the internal combustion engine (1) according to claim 3, wherein a radiator grille closure (70) is located in a front part of the vehicle at a position in front of a front edge of the cylinder head-side heat insulation cover (30) and controls a flow rate of the headwind that is to be introduced into the flow channel in the space between the cylinder head-side heat insulation cover (30) and the internal combustion engine (1). [5] Thermal insulation structure of the internal combustion engine (1) according to one of claims 1 to 4, wherein The lower cylinder head side heat insulation cover (34) of the upper and lower cylinder head side heat insulation covers (33, 34) overlaps an upper section of the cylinder block side heat insulation cover (40) when viewed from the side of the vehicle. [6] Thermal insulation structure of the internal combustion engine (1) according to any one of claims 1 to 5, wherein a matching section of the first side wall (32) of the cylinder head-side thermal insulation cover (30) and the second side wall (43) of the cylinder block-side thermal insulation cover (40) has a vertical length set to 40 mm or more.

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