JP2021188587A - Engine unit - Google Patents

Abstract

To prevent occurrence of knocking in an engine unit by sufficiently lowering a temperature of a cylinder body by using a coolant without increasing the size of and complicating a device for cooling the coolant.SOLUTION: When a temperature of a coolant is in a first low temperature region, the coolant flows in a coolant passage part 41 through a coolant pump device 42, a cylinder head 20C and the coolant pump device 42 in order without passing through a radiator 44 and a cylinder body 20B. When the temperature of the coolant is in a high temperature region higher than the first low temperature region, the coolant flows in the coolant passage part 41 through the coolant pump device 42, the cylinder head 20C, the radiator 44, the cylinder body 20B and the coolant pump device 42 in order.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine unit.

The engine unit disclosed in Patent Document 1 and Patent Document 2 includes a cooling water circuit having a switching valve that switches according to the temperature of the cooling water.

The cooling water of the engine unit of Patent Document 1 flows as follows by the action of the thermostat valve (switching valve) when the temperature is low. That is, the cooling water flows in the order of water pump → cylinder head → water pump. When the temperature of the cooling water is high, the thermostat valve works to allow the cooling water to flow as follows. That is, the cooling water flows in the order of water pump → cylinder head → cylinder body (cylinder block) → radiator → water pump. Since the cooling water hardly flows to the cylinder body at a low temperature, the temperature of the cylinder body rises relatively quickly during the warm-up operation, and the viscosity of the lubricating oil decreases relatively quickly. Therefore, the friction loss of the engine unit during warm-up operation is reduced.

The cooling water of the engine unit of Patent Document 2 flows as follows by the action of the thermostat valve (switching valve) when the temperature is low. That is, the cooling water flows in the order of water pump → cylinder head → water pump. When the temperature of the cooling water is high, the thermostat valve works to allow the cooling water to flow as follows. That is, the cooling water flows in the order of water pump → cylinder head → cylinder body (cylinder block) → radiator → water pump. Since the cooling water is supplied to the cylinder body when the temperature is high, it is possible to lower the temperature of the cylinder body.

Japanese Patent No. 4278131 Japanese Unexamined Patent Publication No. 2002-97959

The inventors of the present application have studied the engine units of Patent Documents 1 and 2. As a result, it has been found that a problem occurs in the engine unit of Patent Documents 1 and 2 if the device for cooling the coolant is not increased in size and / or complicated. That is, it was found that the engine units of Patent Documents 1 and 2 are prone to knocking when the coolant is at a high temperature.

An object of the present invention is to provide an engine unit in which knocking is unlikely to occur even when the device for cooling the coolant is not made large and complicated.

The inventors of the present application obtained the following findings by studying the engine units of Patent Documents 1 and 2. When the temperature of the engine unit of Patent Documents 1 and 2 is high, the cooling water flows out of the radiator and then is supplied to the cylinder body via the water pump and the cylinder head. In other words, the cooling water cooled by the radiator is supplied to the cylinder body after being warmed by the cylinder head. Therefore, it has been found that in the engine units of Patent Documents 1 and 2, the temperature of the cylinder body (particularly the cylinder bore) may not be sufficiently lowered by the cooling water flowing through the cylinder body. Therefore, the temperature of the intake air may rise significantly due to heat exchange between the intake air, which is the air flowing into the cylinder bore during the intake stroke, and the cylinder bore. Therefore, the engine units of Patent Documents 1 and 2 are prone to knocking.

For example, if the magnitude of the pressure that can be generated by the coolant pump device and / or the heat exchange function of the radiator is increased, the temperature of the cylinder body (cylinder bore) can be lowered by the cooling water. However, in this case, the coolant pump device and / or the radiator, which is a device for cooling the cooling water, becomes large and complicated.

The inventors of the present application have found that cooling the cylinder body has a stronger correlation with the difficulty of knocking than cooling the cylinder head. Therefore, the present inventors have come up with the idea of configuring a coolant circuit so that the cooling water flowing out of the radiator is supplied to the cylinder body without passing through the cylinder head when the coolant is at a high temperature. Thereby, the temperature of the cylinder body can be sufficiently lowered by the coolant without increasing the size and complexity of the device for cooling the coolant. As a result, the engine unit is less likely to knock without increasing the size and complexity of the device for cooling the coolant.

(1) The engine unit of the present invention has a cylinder body in which at least one cylinder bore is formed, a cylinder head connected to the cylinder body, and at least a part of the cylinder head passes through the cylinder head and the cylinder body to cool the inside. A coolant pump device provided in a coolant passage portion through which a liquid circulates, a coolant pump device provided in the coolant passage portion, and the coolant is pumped to circulate the coolant in the coolant passage portion, and the coolant passage portion. It is equipped with a radiator provided in the section.
When the temperature of the coolant is in the first low temperature region, the coolant pump device, the cylinder head, and the coolant pump device are passed through the coolant passage portion in this order without passing through the radiator and the cylinder body. When the coolant flows and the temperature of the coolant is in the high temperature region higher than the first low temperature region, the coolant pump device, the cylinder head, the radiator, the cylinder body, and the coolant pump device are in this order. The coolant flows in the coolant passage portion.

According to this configuration, the coolant does not flow to the cylinder body when the temperature of the coolant is in the first low temperature region. Therefore, the temperature of the cylinder body rises relatively quickly when the engine unit is warming up.
Further, when the temperature of the coolant is in the high temperature region, the coolant cooled by the radiator flows directly to the cylinder body. In other words, the coolant cooled by the radiator is supplied to the cylinder body without going through the coolant pump device and the cylinder head. In other words, the coolant cooled by the radiator is supplied to the cylinder body without being heated by the cylinder head. Therefore, the coolant cooled by the radiator can be cylinderd through the coolant pump device and cylinder head without increasing and complicating the coolant pump device and / or radiator, which is a device for cooling the coolant. It is possible to lower the temperature of the cylinder body by the coolant as compared to the case where it is supplied to the body. That is, for example, the temperature of the cylinder body (cylinder bore) can be sufficiently lowered without increasing the magnitude of the pressure that can be generated by the coolant pump device and / or the heat exchange function of the radiator. Therefore, it is possible to suppress a significant increase in the temperature of the intake air due to heat exchange between the intake air, which is the air flowing into the cylinder bore while the engine unit is executing the intake stroke, and the cylinder bore. Therefore, knocking is unlikely to occur in the engine unit even when the coolant pump device and / or the radiator, which is a device for cooling the coolant, is not made large and complicated.

(2) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
When the temperature of the coolant is in the first low temperature region, the coolant pump device, the cylinder head, and the coolant pump device are in this order in the coolant passage portion without passing through the radiator and the cylinder body. When the coolant is in the first state to allow the coolant to flow and the temperature of the coolant is in the high temperature region, the coolant pump device, the cylinder head, the radiator, the cylinder body, and the coolant are A switching valve configured to be in a second state for allowing the coolant to flow in the coolant passage in the order of the pump device is provided in the coolant passage.

According to this configuration, the switching valve controls the flow of the coolant according to the temperature of the coolant. Therefore, knocking is unlikely to occur in the engine unit without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant.

(3) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration in addition to the configuration of (2) above.
The switching valve has a first inlet into which the cooling liquid flowing out of the cylinder head flows in, a first outlet allowing the cooling liquid to flow out toward the radiator, and the cooling liquid flowing out of the cylinder body. A four-way valve with an inflowing second inlet and a second outlet allowing the coolant to flow out towards the coolant pump device.
The four-way valve allows the coolant flowing into the first inlet to flow out from the second outlet, and the coolant flowing into the second inlet flows out from the first outlet and the second outlet. The first state and the coolant flowing into the first inlet are made to flow out from the first outlet, and the coolant flowing into the second inlet is made to flow out from the second outlet. It is configured to be switched to the second state.
When the temperature of the coolant is in the first low temperature region, the four-way valve is in the first state, so that the coolant pump device and the cylinder head do not pass through the radiator and the cylinder body. When the coolant circulates in the coolant passage portion and the temperature of the coolant is in the high temperature region, the four-way valve is the second valve in this order. When the state is set, the coolant is in the order of the coolant pump device, the cylinder head, the four-way valve, the radiator, the cylinder body, the four-way valve, and the coolant pump device, and the coolant passes through the coolant passage. It circulates in the department.

According to this configuration, by using one switching valve (four-way valve), the coolant circulates in the coolant passage portion so as to sufficiently lower the temperature of the cylinder body. That is, the significant increase in the temperature of the intake air due to the heat exchange between the intake air and the cylinder bore is suppressed by using one switching valve. Therefore, knocking is unlikely to occur in the engine unit without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant.

(4) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration in addition to the configuration of (2) above.
The switching valve is located outside the cylinder head and the cylinder body, and is separate from the cylinder head and the cylinder body.

(5) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration in addition to the configuration of (2) above.
When the switching valve is in the first state, at least one of the coolant and air flows into the coolant passage portion formed in the cylinder body via the radiator.
The engine unit has a bypass passage portion connected to the coolant passage portion in the cylinder body and connected to the coolant passage portion in the cylinder head.

When the switching valve is in the first state, a small amount of coolant and at least one of the air may pass through the switching valve and flow into the coolant passage portion formed in the cylinder body via the radiator. Then, at least one of the small amount of the coolant and the air exerts pressure on at least one of the coolant and the air in the coolant passage portion formed in the cylinder body. Therefore, at least one of the coolant and the air in the coolant passage portion formed in the cylinder body flows into the coolant passage portion formed in the cylinder head through the internal space of the bypass passage portion.
When a small amount of coolant stays in the coolant passage portion formed in the cylinder body, the coolant rapidly becomes hot due to receiving heat from the cylinder body. Also, air has a lower thermal conductivity than the coolant. Therefore, when air stays in the coolant passage portion formed in the cylinder body, the temperature of the cylinder body tends to be excessively high. Therefore, if at least one of the coolant and the air is in such a state, the temperature of the cylinder body may become excessively high.
According to this configuration, even when the switching valve is in the first state, it is difficult for the coolant and air to stay in the coolant passage portion formed in the cylinder body. Therefore, the temperature of the cylinder body is sufficiently set when the switching valve is in the second state without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant. It is possible to reduce it. Therefore, it is possible to suppress a significant increase in the temperature of the intake air due to heat exchange between the intake air and the cylinder bore. Therefore, knocking is unlikely to occur in the engine unit without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant.

(6) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
The engine unit has a crankshaft.
The coolant pump device is configured to switch between a stopped state and an operating state independently of the movement of the crankshaft.

According to this configuration, for example, when the temperature of the coolant is lower than the first low temperature region and the engine unit is in the operating state, the coolant pump device is stopped. Then, the temperature of the cylinder head and the cylinder body becomes high. For example, when the temperature of the coolant subsequently reaches the high temperature region, the coolant pump device is switched to the operating state. Then, the coolant cooled by the radiator flows to the cylinder body without passing through the cylinder head. Therefore, it is possible to sufficiently lower the temperature of the cylinder body without increasing the size and complexity of the coolant pump device and / or the radiator, which is a device for cooling the coolant. Therefore, it is possible to suppress a significant increase in the temperature of the intake air due to heat exchange between the intake air and the cylinder bore. Therefore, knocking is unlikely to occur in the engine unit without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant.

(7) According to one aspect of the present invention, the engine unit of the present invention preferably has the following configuration in addition to the configuration of (6) above.
The coolant pump device is configured to be in the stopped state when the temperature of the coolant is in the second low temperature region lower than the first low temperature region.

According to this configuration, the coolant pump device is stopped when the temperature of the coolant is in the second low temperature region and the engine unit is in the operating state. Then, the temperature of the cylinder head and the cylinder body becomes high. For example, when the temperature of the coolant subsequently reaches the high temperature region, the coolant pump device is switched to the operating state. Then, the coolant cooled by the radiator is supplied to the cylinder body without passing through the cylinder head. Therefore, it is possible to sufficiently lower the temperature of the cylinder body without increasing the size and complexity of the coolant pump device and / or the radiator, which is a device for cooling the coolant. Therefore, it is possible to suppress a significant increase in the temperature of the intake air due to heat exchange between the intake air and the cylinder bore. Therefore, knocking is unlikely to occur in the engine unit without increasing the size and complexity of the coolant pump device and / or the radiator, which are devices for cooling the coolant.

(8) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
The engine unit has at least one piston that reciprocates within the at least one cylinder bore along a cylinder axis that is the central axis of the cylinder bore.
The diameter of the at least one cylinder bore is the first diameter, and the stroke of the piston that reciprocates in the cylinder bore having the first diameter is the first stroke longer than the first diameter.

According to this configuration, the engine unit is a long stroke engine unit.
When the displacement of the long stroke engine unit and the short stroke engine unit are the same, the length in the direction parallel to the cylinder axis, which is the central axis of the cylinder bore, is relative to the long stroke engine unit in the long stroke engine unit. To long. Therefore, since the contact area between the inner surface of the cylinder bore and the intake air is large, the amount of increase in the temperature of the intake air of the long stroke engine unit is relatively larger than that of the short stroke engine unit. When the engine rotation speeds of the long stroke engine unit and the short stroke engine unit are the same, the long stroke engine unit has a higher average piston speed than the short stroke engine unit. Therefore, the intake speed of the intake air is higher in the long stroke engine unit than in the short stroke engine unit. Therefore, the heat transfer coefficient, which increases in proportion to the magnitude of fluid turbulence, is larger in the long stroke engine unit than in the short stroke engine unit. Therefore, the temperature rise of the intake air of the long stroke engine unit is larger than that of the short stroke engine unit.
According to this configuration, when the temperature of the coolant is in the high temperature region, the temperature of the cylinder body without increasing and / or complicating the coolant pump device and / or radiator, which is a device for cooling the coolant. Can be sufficiently reduced.
Therefore, when the temperature of the coolant is in the high temperature region, the temperature of the cylinder body of the long stroke engine unit can be sufficiently lowered by the coolant. As a result, it is possible to suppress heat exchange between the intake air and the cylinder bore during the intake stroke and reduce the amount of temperature rise of the intake air. Therefore, knocking is unlikely to occur in the long stroke engine unit.

(9) From one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
The engine unit is formed in a combustion chamber in which an intake port is formed, a first intake passage portion formed in the cylinder head and connected to the intake port, and an upstream end in the air flow direction of the first intake passage portion. A second intake passage portion arranged outside the cylinder head, which is connected to and has a throttle valve, and a fuel injection device for injecting fuel in the first intake passage portion or in the second intake passage portion. Has.

According to this configuration, the engine unit includes a fuel injection device that injects fuel in the first intake passage portion or the second intake passage portion. Therefore, the temperature of the cylinder head and the cylinder body tends to be higher than that of the direct injection type engine unit provided with the fuel injection device for injecting fuel in the combustion chamber. Therefore, the cooling liquid has a great cooling effect on the cylinder head and the cylinder body.

(10) According to one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
The engine unit has a spark plug that ignites a mixture of air and fuel in the combustion chamber.

(11) According to one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
The cylinder axis, which is the central axis of the cylinder bore, is inclined with respect to the vertical direction of the vehicle on which the engine unit is mounted.
The engine unit is formed in a combustion chamber in which an exhaust port is formed, a first exhaust passage portion formed in the cylinder head and connected to the exhaust port, and a downstream end in the gas flow direction of the first exhaust passage portion. It has a second exhaust passage portion connected to the outside of the cylinder head.
When the vertical direction of the vehicle on which the engine unit is mounted is set to the vertical direction, the downstream end of the first exhaust passage portion is formed on the downward outer surface of the cylinder head.

(12) According to one aspect of the present invention, the engine unit of the present invention preferably has the following configuration.
Only one cylinder bore is formed in the cylinder body.

<Definition of terms>
In the present invention, the coolant means a liquid having a cooling function. The coolant contains cooling water. Cooling water is a liquid containing water. The coolant may be a liquid that does not contain water. The coolant does not contain lubricating oil for lubricating pistons and the like. The coolant may or may not contain oil other than the lubricating oil.

In the present invention, "when the switching valve is in the first state, at least one of the coolant and the air flows into the coolant passage portion formed in the cylinder body via the radiator" means that the switching valve is in the first state. When the coolant is in, a smaller amount of coolant per unit time than the coolant that passes through the switching valve and flows into the coolant pump device passes through the switching valve and is formed on the cylinder body via the radiator. Air flowing into the passage and / or when the switching valve is in the first state, less air per unit time than air flowing through the switching valve and into the coolant pumping device presses the switching valve. It means that it passes through and flows into the coolant passage portion formed in the cylinder body through the radiator.

In the present invention, "the coolant pump device is switched between a stopped state and an operating state independently of the movement of the crankshaft" means that the coolant pump device is in a stopped state regardless of the movement of the crankshaft. It means that it can be switched between the operating state and the operating state. That is, the coolant pump device can be in either the stopped state or the operating state when the crankshaft is not rotating. Further, when the crankshaft is rotating, the coolant pump device can be in a stopped state or an operating state.

In the present invention and the present specification, the vertical direction of the vehicle means the vertical direction of the personal watercraft when the personal watercraft floating in still water is in a stationary state when the vehicle is a personal watercraft which is a saddle-type vehicle. be.

In the present invention and the present specification, the fact that the cylinder axis intersects the vertical direction of the vehicle on which the engine unit is mounted means that the cylinder axis is horizontal.

In the present invention and the present specification, rotation is not limited to rotation of 360 ° or more. Rotations herein also include rotations of less than 360 °. The definitions of forward and reverse rotation are similar to this definition of rotation. Swinging herein means a rotation of less than 360 °.

In the present invention and the present specification, the end portion of a certain component means a portion where the end portion of the component and the vicinity thereof are combined.

As used herein, the term "and / or" includes any or all combinations of one or more related enumerated constructs.

The passage portion in the present invention means a wall body or the like that surrounds the path and forms the path. The route means the space through which the object passes. For example, this definition applies to coolant passages, bypass passages, intake passages, and exhaust passages.

In the present specification, the fact that A is in the front direction of B refers to the following state unless otherwise specified. A is in the front space of the two spaces separated by a plane that passes through the foremost end of B and is orthogonal to the front-rear direction. A and B may or may not be arranged in the front-rear direction. When B is a plane or a straight line orthogonal to the front-rear direction, the plane passing through the foremost end of B is a plane passing through B. If B is a straight line or plane with an infinite length in the anteroposterior direction, the foremost end of B is not specified. A straight line or plane having an infinite length in the front-back direction is not limited to a straight line or plane parallel to the front-back direction.
The same definition applies to the expression that A is behind B under the same conditions for B. The same definition also applies to the expression that A is above or below B and A is to the right or left of B under similar conditions for B.

As used herein, the use of the terms "comprising" or "having" and variations thereof are described features, processes, operations, elements, components and / or their use. It identifies the existence of an equivalent, but can include one or more of steps, actions, elements, components, and / or groups thereof.

In the present invention, the terms connected, connected, coupled, supported are used in a broad sense. Specifically, it includes not only direct mounting, connection, coupling and support, but also indirect mounting, connection, coupling and support. Moreover, connected and coupled are not limited to physical or mechanical connections / connections. They also include direct or indirect electrical connections / couplings.

Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Terms such as those defined in commonly used dictionaries should be construed to have meaning consistent with the relevant technology and in the context of the present disclosure and are expressly defined herein. Unless done, it will not be interpreted in an idealized or overly formal sense.

As used herein, the term "favorable" is non-exclusive. "Preferable" means "preferable, but not limited to". In the present specification, the configuration described as "preferable" exhibits at least the above-mentioned effect obtained by the above-mentioned configuration (1). Also, as used herein, the term "may" is non-exclusive. "May" means "may be, but is not limited to". In the present specification, the configuration described as “may” exhibits at least the above-mentioned effect obtained by the above-mentioned configuration (1).

If the number of components is not explicitly specified in the claims and is displayed in the singular when translated into English, the present invention may have a plurality of the components. .. Further, the present invention may have only one of these components.

The present invention does not limit the combination of the preferred configurations described above to each other. Prior to discussing embodiments of the invention in detail, it should be understood that the invention is not limited to the details of component configuration and arrangement described in the following description or illustrated in the drawings. The present invention is also possible in embodiments other than the embodiments described later. The present invention can also be an embodiment in which various modifications are made to the embodiment described later. In addition, the present invention can be carried out by appropriately combining embodiments and modifications described later.

In the engine unit of the present invention, knocking is unlikely to occur in the engine unit even when the device for cooling the coolant is not made large and complicated.

It is a schematic block diagram of the engine unit of embodiment of this invention. It is a right side view of the motorcycle which concerns on the specific example of embodiment of this invention. It is a schematic diagram for demonstrating the structure of an engine unit. It is a schematic diagram of the engine unit for demonstrating the flow of the coolant when the temperature of the coolant is in the first low temperature region. It is a schematic diagram of the engine unit for demonstrating the flow of the coolant when the temperature of the coolant is in a high temperature region.

<Embodiment of the present invention>
Hereinafter, embodiments of the present invention will be described with reference to FIG. The engine unit 11 of the embodiment of the present invention includes a cylinder body 20B, a cylinder head 20C, a coolant passage portion 41, a coolant pump device 42, and a radiator 44.

At least one cylinder bore 20Ba is formed in the cylinder body 20B. The cylinder head 20C is connected to the cylinder body 20B. At least a part of the coolant passage portion 41 passes through the cylinder head 20C and the cylinder body 20B. The coolant can circulate inside the coolant passage portion 41. The coolant pump device 42 is provided in the coolant passage portion 41. The coolant pump device 42 pumps the coolant to circulate the coolant in the coolant passage 41. The radiator 44 is provided in the coolant passage portion 41.

When the temperature of the coolant is in the first low temperature region, the engine unit 11 does not pass through the radiator 44 and the cylinder body 20B, but the coolant pump device 42, the cylinder head 20C, and the coolant pump device 42 in this order. It is configured so that the coolant flows in the passage portion 41. When the temperature of the coolant is in the high temperature region higher than the first low temperature region, the engine unit 11 has the coolant pump device 42, the cylinder head 20C, the radiator 44, the cylinder body 20B, and the coolant pump device 42 in this order. It is configured so that the coolant flows in the passage portion 41.

When the temperature of the coolant of the engine unit 11 of the embodiment of the present invention is in the first low temperature region, the coolant does not flow to the cylinder body 20B. Therefore, when the engine unit 11 warms up, the temperature of the cylinder body 20B rises relatively quickly.

Further, when the temperature of the coolant is in the high temperature region, the coolant cooled by the radiator 44 flows directly to the cylinder body 20B. In other words, the coolant cooled by the radiator 44 is supplied to the cylinder body 20B without going through the coolant pump device 42 and the cylinder head 20C. In other words, the coolant cooled by the radiator 44 is supplied to the cylinder body 20B without being heated by the cylinder head 20C. Therefore, the coolant cooled by the radiator 44 is the coolant pump device 42 and the cylinder head without increasing the size and complexity of the coolant pump device 42 and / or the radiator 44, which is a device for cooling the coolant. It is possible to further lower the temperature of the cylinder body 20B by the coolant as compared with the case where it is supplied to the cylinder body 20B via the 20C. That is, for example, it is possible to sufficiently lower the temperature of the cylinder body 20B (cylinder bore 20Ba) without increasing the magnitude of the pressure that can be generated by the coolant pump device 42 and / or the heat exchange function of the radiator 44. Become. Therefore, it is possible to suppress a significant increase in the temperature of the intake air due to heat exchange between the intake air, which is the air flowing into the cylinder bore 20Ba, and the cylinder bore 20Ba while the engine unit 11 is executing the suction stroke.

Therefore, knocking is unlikely to occur in the engine unit 11 without increasing the size and complexity of the coolant pump device 42 and / or the radiator 44, which is a device for cooling the coolant.

<Specific example of embodiment>
Next, a specific example of the above-described embodiment of the present invention will be described with reference to FIGS. 2 to 5. In the following description, the description of the same parts as those of the above-described embodiment of the present invention will be omitted. Specific examples are included in the above-described embodiments of the present invention. A specific example of the present embodiment is an example in which the present invention is applied to the motorcycle 1. In the following description, unless otherwise specified, the front-rear direction is the front-rear direction of the vehicle. The front-rear direction of the vehicle is the front-rear direction seen from the rider seated on the seat 5 described later of the motorcycle 1. In the following description, the left-right direction is the left-right direction of the vehicle. The left-right direction of the vehicle is the left-right direction seen from the rider seated on the seat 5 described later of the motorcycle 1. The left-right direction of the vehicle is also the vehicle width direction of the motorcycle 1. Less than. The vertical direction of the vehicle is the vertical direction in a state where the motorcycle 1 in which all the wheels are in contact with the horizontal road surface is upright on the horizontal road surface. The vehicle front-rear direction, the vehicle left-right direction, and the vehicle up-down direction are orthogonal to each other. In the description of FIG. 2, unless otherwise specified, the arrow F, the arrow B, the arrow U, and the arrow D indicating that the vertical direction is the vertical direction of the vehicle are forward, backward, upward, and downward, respectively. Represents.

[1] Schematic configuration of a motorcycle As shown in FIG. 2, the motorcycle 1 includes a front wheel 2, a rear wheel 3, and a vehicle body frame 4. A seat 5 is supported on the upper part of the vehicle body frame 4. The engine unit 11 is supported on the vehicle body frame 4. Further, the vehicle body frame 4 supports a battery (not shown) that supplies electric power to electronic devices such as an ECU (Electronic Control Unit) 80 described later of the engine unit 11, a coolant pump device 42, and various sensors.

[2] Configuration of Engine Unit The configuration of the engine unit 11 will be described below. FIG. 3 is a schematic diagram showing the configuration of the engine unit 11. The engine unit 11 includes an engine main body 20, a cooling unit 40, an external intake passage portion 51, and an external exhaust passage portion 61. The cooling unit 40, the external intake passage portion 51, and the external exhaust passage portion 61 are located outside the engine body 20. Inside the engine body 20, at least a part of a crankshaft 21, a piston 22, an intake valve 25, an exhaust valve 26, a spark plug 27, and a fuel injection device 28 is arranged. The engine unit 11 is a single cylinder engine unit. The engine unit 11 is a 4-stroke engine that repeats an intake stroke, a compression stroke, a combustion stroke (expansion stroke), and an exhaust stroke.

The engine body 20 has a crankcase 20A, a cylinder body 20B, a cylinder head 20C, and a head cover 20D. These are connected in this order. The crankshaft 21 is rotatably provided on the crankcase 20A. The rotation center axis of the crankshaft 21 is parallel to the left-right direction. The crankcase 20A has an oil pan for storing lubricating oil. An oil pump (not shown) for pumping lubricating oil is arranged inside the crankcase 20A. The oil pump operates by the rotational force of the crankshaft 21. The head cover 20D may be integrated with the cylinder head 20C.

The cylinder body 20B has a cylinder bore 20Ba. The cylinder axis 20X, which is the central axis of the cylinder bore 20Ba, is inclined with respect to the vertical direction. As shown in FIG. 2, when the engine unit 11 is viewed in the left-right direction, the upper portion of the cylinder axis 20X is located in front of the lower portion. When the engine unit 11 is viewed in the left-right direction, the inclination angle of the cylinder axis 20X with respect to the vertical direction is larger than 0 ° and 45 ° or less. The cylinder axis 20X is not a line segment existing only in the region where the cylinder bore 20Ba exists, but a straight line extending infinitely. The piston 22 is provided in the cylinder bore 20Ba so as to be reciprocating along the cylinder axis 20X. The piston 22 is connected to the crankshaft 21 via a connecting rod 23. As shown in FIG. 3, the first stroke St, which is the stroke during the reciprocating movement of the piston 22, is longer than the first diameter Db, which is the diameter of the cylinder bore 20Ba. That is, the engine unit 11 of the specific example is a long stroke engine unit.

The engine body 20 has a combustion chamber 24, a cylinder head intake passage portion 20Ca, and a cylinder head exhaust passage portion 20Cb. In addition, in this specification, a passage part means a structure forming a path. The combustion chamber 24 is formed by a cylinder head 20C, a cylinder bore 20Ba, and a piston 22. The combustion chamber 24 has an intake port 24a and an exhaust port 24b formed in the cylinder head 20C. Air is supplied to the combustion chamber 24 from the intake port 24a. The exhaust gas generated in the combustion chamber 24 is discharged from the exhaust port 24b. The cylinder head intake passage portion 20Ca and the cylinder head exhaust passage portion 20Cb are formed in the cylinder head 20C. The cylinder head intake passage portion 20Ca is connected to the intake port 24a. The cylinder head exhaust passage portion 20Cb is connected to the exhaust port 24b.

The upstream end of the cylinder head intake passage portion 20Ca in the air flow direction is connected to the external intake passage portion 51. A throttle valve 52 is arranged in the external intake passage portion 51. The air in the atmosphere is supplied to the combustion chamber 24 through the external intake passage portion 51 and the cylinder head intake passage portion 20Ca.

The downstream end of the cylinder head exhaust passage portion 20Cb in the exhaust gas flow direction is an opening (not shown) formed in the front surface 20C3 of the cylinder head 20C. The front surface 20C3 is a downward outer surface of the cylinder head 20C. The downstream end of the cylinder head exhaust passage portion 20Cb in the exhaust gas flow direction is connected to the external exhaust passage portion 61. A catalyst (not shown) for purifying the exhaust gas is arranged in the external exhaust passage portion 61. The exhaust gas generated in the combustion chamber 24 is discharged to the atmosphere through the cylinder head exhaust passage portion 20Cb and the external exhaust passage portion 61.

The intake valve 25 is provided on the cylinder head 20C so as to open and close the intake port 24a. The exhaust valve 26 is provided in the cylinder head 20C so as to open and close the exhaust port 24b. The intake valve 25 and the exhaust valve 26 are driven by a valve drive mechanism (not shown).

As shown in FIG. 3, the tip of the spark plug 27 is arranged in the combustion chamber 24. The spark plug 27 ignites an air-fuel mixture containing fuel (for example, gasoline) and air in the combustion chamber 24. The fuel injection device 28 is provided in the cylinder head 20C so as to inject fuel in the cylinder head intake passage portion 20Ca. The fuel injection device 28 may be arranged so as to inject fuel in the external intake passage portion 51.

A part of the coolant passage portion 41 is formed inside the engine main body 20. The coolant circulates in the coolant passage portion 41. The coolant passage portion 41 includes a cylinder head coolant passage portion 41b, a cylinder body coolant passage portion 41f, and a bypass passage portion 41g formed inside the engine body 20. The cylinder head coolant passage portion 41b is formed inside the cylinder head 20C. The upstream end of the cylinder head coolant passage portion 41b in the coolant flow direction is the first opening 20C1 (see FIGS. 4 and 5) formed on the outer surface of the cylinder head 20C. The downstream end of the cylinder head coolant passage portion 41b is a second opening 20C2 (see FIGS. 4 and 5) formed on the outer surface of the cylinder head 20C. The cylinder body coolant passage portion 41f is formed inside the cylinder body 20B. The upstream end of the cylinder body coolant passage portion 41f in the coolant flow direction is the third opening 20B1 (see FIGS. 4 and 5) formed on the outer surface of the cylinder body 20B. The downstream end of the cylinder body coolant passage portion 41f is a fourth opening 20B2 (see FIGS. 4 and 5) formed on the outer surface of the cylinder body 20B. The bypass passage portion 41g is formed inside the cylinder body 20B and the cylinder head 20C. The upstream end of the bypass passage portion 41g in the flow direction of the coolant is connected to the cylinder body coolant passage portion 41f. The downstream end of the bypass passage portion 41g in the coolant flow direction is connected to the cylinder head coolant passage portion 41b. The cylinder head 20C is provided with a coolant temperature sensor 29 that detects the temperature of the coolant flowing through the coolant passage portion 41.

As shown in FIGS. 2 to 5, the cooling unit 40 of the engine unit 11 has a coolant pump device 42, a switching valve 43, a radiator 44, and a fan (not shown). Further, the cooling unit 40 includes a part of the coolant passage portion 41.

The coolant pump device 42 is an electric coolant pump device. The coolant pump device 42 can be fixed to any part of the engine body 20. In the example of FIG. 3, the coolant pump device 42 is fixed to the outer surface of the crankcase 20A. The coolant pump device 42 includes an electric motor and a pump that is rotated by the driving force of the electric motor. The electric motor rotates when the power of the battery is supplied. The coolant pump device 42 is switched between a stopped state and an operating state independently of the movement of the crankshaft 21 and the camshaft that rotates in conjunction with the crankshaft 21. That is, when the crankshaft 21 is not rotating, the coolant pump device 42 can be in either a stopped state or an operating state. Further, when the crankshaft 21 is rotating, the coolant pump device 42 can be in a stopped state or an operating state.

The switching valve 43 is a thermostat valve. The switching valve 43 is fixed to at least one outer surface of the cylinder body 20B and the cylinder head 20C. The switching valve 43 is separate from the cylinder body 20B and the cylinder head 20C. As shown in FIGS. 4 and 5, the case 43a of the switching valve 43 is formed with a first inlet 43b1, a second inlet 43b2, a first outlet 43c1, and a second outlet 43c2. That is, the switching valve 43 is a four-way valve. Inside the case 43a, a movable valve body 43d that can move between the low temperature position and the high temperature position is provided. The movable valve body 43d moves from the low temperature position to the high temperature position or from the high temperature position to the low temperature position depending on the temperature of the coolant flowing through the switching valve 43.

When the temperature of the coolant is in the first low temperature region and in the second low temperature region lower than the first low temperature region, the movable valve body 43d is located at the low temperature position shown in FIG. That is, the movable valve body 43d is located at the low temperature position shown in FIG. 4 when the temperature of the coolant in the case 43a is in either the first low temperature region or the second low temperature region. The state of the switching valve 43 at this time is the first state. When the temperature of the coolant is in the high temperature region higher than the first low temperature region, the movable valve body 43d is located at the high temperature position shown in FIG. That is, when the temperature of the coolant in the case 43a is in the high temperature region, the movable valve body 43d is located at the high temperature position shown in FIG. The state of the switching valve 43 at this time is the second state. The switching valve 43 may be any type of thermostat valve. For example, the switching valve 43 may be a mechanical thermostat valve using a bimetal. The switching valve 43 may be an inflatable thermostat valve using wax. As shown in FIG. 2, the radiator 44 is arranged in front of the upper part of the engine body 20. A fan (not shown) is provided between the engine body 20 and the radiator 44.

The first inlet 43b1 of the switching valve 43 is connected to the second opening 20C2 which is the downstream end of the cylinder head coolant passage portion 41b. The second inlet 43b2 of the switching valve 43 is connected to the fourth opening 20B2 which is the downstream end of the cylinder body coolant passage portion 41f.

The cooling unit 40 has a first passage portion 41a, a second passage portion 41c, a radiator feed passage portion 41d, and a radiator return passage portion 41e. The first passage portion 41a, the second passage portion 41c, the radiator feed passage portion 41d, and the radiator return passage portion 41e are included in the coolant passage portion 41. The upstream end of the first passage portion 41a in the flow direction of the coolant is connected to the coolant pump device 42. The downstream end of the first passage portion 41a is connected to the first opening 20C1 which is the upstream end of the cylinder head coolant passage portion 41b. The upstream end of the second passage portion 41c in the flow direction of the coolant is connected to the second outlet 43c2 of the switching valve 43. The downstream end of the second passage portion 41c is connected to the coolant pump device 42. The upstream end of the radiator feed passage portion 41d in the flow direction of the coolant is connected to the first outlet 43c1 of the switching valve 43. The downstream end of the radiator feed passage portion 41d is connected to the radiator 44. The upstream end of the radiator return passage portion 41e in the flow direction of the coolant is connected to the radiator 44. The downstream end of the radiator return passage portion 41e is connected to the third opening 20B1 which is the upstream end of the cylinder body coolant passage portion 41f.

The ECU 80 (see FIG. 2) controls the operation of the engine unit 11. The ECU 80 controls the spark plug 27, the fuel injection device 28, the coolant pump device 42, and the like. The ECU 80 includes a processor (arithmetic processing unit) and a memory. The ECU 80 may be composed of a plurality of devices arranged at distant positions. The ECU 80 is electrically connected to various sensors such as the coolant temperature sensor 29.

[3] Flow of Coolant in Cooling Unit When the engine unit 11 is started, the ECU 80 controls the coolant pump device 42 based on the detection result transmitted from the coolant temperature sensor 29. When the temperature of the coolant detected by the coolant temperature sensor 29 is in the second low temperature region, the power of the battery is not supplied to the coolant pump device 42 under the control of the ECU 80. Therefore, when the temperature of the coolant detected by the coolant temperature sensor 29 is in the second low temperature region, the coolant pump device 42 is stopped. At this time, the movable valve body 43d of the switching valve 43 is located at the low temperature position shown in FIG. At this time, the movable valve body 43d allows the coolant to flow from the first inlet 43b1 to the second outlet 43c2. When the engine unit 11 starts, the temperatures of the cylinder body 20B and the cylinder head 20C rise. Then, the heat of the cylinder body 20B and the cylinder head 20C is transferred to the coolant. Therefore, a small amount of coolant is supplied from the coolant pump device 42 → the first passage portion 41a → the cylinder head coolant passage portion 41b → the first inlet 43b1 → the second outlet 43c2 → the second passage portion 41c → the coolant pump device 42. Convection occurs in the coolant passage portion 41 in order. On the other hand, at this time, the movable valve body 43d almost prevents the cooling liquid from flowing from the first inlet 43b1 to the first outlet 43c1, and the cooling liquid from the second inlet 43b2 to the first outlet 43c1 and the second outlet 43c2. Prevents the flow. However, at this time, at least one of the coolant and the air slightly flows from the first inlet 43b1 to the first outlet 43c1.
As described above, when the temperature of the coolant is in the second low temperature region, the coolant inside the cylinder body 20B and the inside of the cylinder head 20C hardly flows. Therefore, when the engine unit 11 is started, the temperatures of the cylinder body 20B and the cylinder head 20C rise relatively quickly, and the viscosity of the lubricating oil flowing through the engine body 20 decreases relatively quickly. Therefore, the friction loss of the engine unit 11 is reduced when the engine unit 11 is started.

Further, when the temperature of the coolant is in the second low temperature region, the coolant convected in the radiator return passage portion 41e flows into the cylinder body coolant passage portion 41f provided inside the cylinder body 20B. Then, due to the pressure of the coolant flowing into the cylinder body coolant passage portion 41f, at least one of the coolant and the air existing in the cylinder body coolant passage portion 41f passes through the bypass passage portion 41g to cool the cylinder head. It flows to the liquid passage portion 41b. If the coolant passage portion 41 does not include the bypass passage portion 41g, a small amount of coolant in the cylinder body coolant passage portion 41f may boil due to the heat of the cylinder body 20B. However, since the coolant passage portion 41 of the specific example includes the bypass passage portion 41g, the coolant in the cylinder body coolant passage portion 41f flows through the bypass passage portion 41g to the cylinder head coolant passage portion 41b. Therefore, there is little possibility that the coolant in the cylinder body coolant passage portion 41f will boil. Further, if the coolant passage portion 41 does not include the bypass passage portion 41g and air is present in the coolant passage portion 41, the air may remain in the cylinder body coolant passage portion 41f. Air has a lower thermal conductivity than the coolant. Therefore, when air remains in the cylinder body coolant passage portion 41f, it becomes difficult for the cylinder body 20B to be cooled. However, since the coolant passage portion 41 of the specific example includes the bypass passage portion 41g, no air remains in the cylinder body coolant passage portion 41f. Therefore, the cylinder body 20B can be cooled by the coolant in the cylinder body coolant passage portion 41f. Even when the temperature of the coolant is in the first low temperature region and the high temperature region, at least one of the coolant and the air in the cylinder body coolant passage portion 41f passes through the bypass passage portion 41g and the cylinder head coolant passage. It flows to the portion 41b.

When the temperature of the coolant detected by the coolant temperature sensor 29 is in the first low temperature region, the electric power of the battery is supplied to the coolant pump device 42 under the control of the ECU 80. Therefore, the coolant pump device 42 operates to pump the coolant in the coolant passage 41. Further, the movable valve body 43d of the switching valve 43 is located at the low temperature position shown in FIG. Therefore, the coolant circulates in the coolant passage portion 41 along the direction of the arrow in FIG. That is, the coolant is in the order of the coolant pump device 42 → the first passage portion 41a → the cylinder head coolant passage portion 41b → the first inlet 43b1 → the second outlet 43c2 → the second passage portion 41c → the coolant pump device 42. It circulates in the coolant passage portion 41. As described above, at this time, the movable valve body 43d almost prevents the coolant from flowing from the first inlet 43b1 to the first outlet 43c1. Therefore, the coolant in the switching valve 43 hardly flows to the radiator feed passage portion 41d, the radiator 44, the radiator return passage portion 41e, and the cylinder body coolant passage portion 41f. As described above, when the temperature of the coolant is in the first low temperature region, the coolant hardly flows to the cylinder body 20B. Therefore, when the engine unit 11 is started, the temperature of the cylinder body 20B rises relatively quickly, and the viscosity of the lubricating oil in the engine body 20 decreases relatively quickly. Therefore, the friction loss of the engine unit 11 is reduced when the engine unit 11 is started.

When the temperature of the coolant detected by the coolant temperature sensor 29 is in the high temperature region, the electric power of the battery is supplied to the coolant pump device 42 under the control of the ECU 80. Therefore, the coolant pump device 42 operates to pump the coolant in the coolant passage 41. Further, the movable valve body 43d of the switching valve 43 is located at the high temperature position shown in FIG. Therefore, the coolant circulates in the coolant passage portion 41 along the direction of the arrow in FIG. That is, the coolant is the coolant pump device 42 → the first passage portion 41a → the cylinder head coolant passage portion 41b → the first inlet 43b1 → the first outlet 43c1 → the radiator feed passage portion 41d → the radiator 44 → the radiator return passage portion 41e. → Cylinder body coolant passage 41f → 2nd inlet 43b2 → 2nd outlet 43c2 → 2nd passage 41c → Coolant pump device 42 circulates in the coolant passage 41 in this order.
When the temperature of the coolant is in the high temperature region as described above, the coolant cooled by the radiator 44 is supplied to the cylinder body 20B without going through the coolant pump device 42 and the cylinder head 20C. Therefore, it is possible to lower the temperature of the cylinder body 20B by the coolant. Therefore, knocking is unlikely to occur in the engine unit 11. Knocking is a phenomenon in which a metallic striking sound or striking vibration is generated due to abnormal combustion occurring in a combustion chamber.

The specific examples of the embodiment of the present invention have been described above. Specific examples of the embodiment of the present invention exert the following effects in addition to the effects of the above-described embodiment of the present invention.

In the engine unit 11 of the specific example, by using one switching valve 43, the coolant is circulated in the coolant passage portion 41 so as to sufficiently lower the temperature of the cylinder body 20B. That is, the temperature of the intake air, which is the air sucked into the combustion chamber 24, is significantly increased by the heat exchange between the intake air and the cylinder bore, which is suppressed by using one switching valve 43. Therefore, knocking is unlikely to occur in the engine unit 11 without increasing the size and complexity of the coolant pump device 42 and / or the radiator 44, which is a device for cooling the coolant.

The coolant pump device 42 is an electric coolant pump device configured to be able to switch between a stopped state and an operating state independently of the movement of the crankshaft 21. Therefore, it is possible to stop the coolant pump device 42 when the temperature of the coolant is in the second low temperature region and the engine unit 11 is in the operating state. Therefore, when the engine unit 11 is started, the temperatures of the cylinder body 20B and the cylinder head 20C rise relatively quickly, and the viscosity of the lubricating oil in the engine body 20 decreases relatively quickly. Therefore, the friction loss of the engine unit 11 is reduced when the engine unit 11 is started.

The engine unit 11 of the specific example is a long stroke engine unit. When the displacement of the long stroke engine unit and the short stroke engine unit are the same, the length in the direction parallel to the cylinder axis, which is the central axis of the cylinder bore, is relative to the long stroke engine unit in the long stroke engine unit. To long. Therefore, since the contact area between the inner surface of the cylinder bore and the intake air is large, the amount of increase in the temperature of the intake air of the long stroke engine unit is relatively larger than that of the short stroke engine unit. When the engine rotation speeds of the long stroke engine unit and the short stroke engine unit are the same, the long stroke engine unit has a higher average piston speed than the short stroke engine unit. Therefore, the intake speed of the intake air is higher in the long stroke engine unit than in the short stroke engine unit. Therefore, the heat transfer coefficient, which increases in proportion to the magnitude of fluid turbulence, is larger in the long stroke engine unit than in the short stroke engine unit. Therefore, the temperature rise of the intake air of the long stroke engine unit is larger than that of the short stroke engine unit. The engine unit 11 of the specific example does not require the size and complexity of the coolant pump device 42 and / or the radiator 44, which is a device for cooling the coolant when the temperature of the coolant is in the high temperature region. , It is possible to sufficiently lower the temperature of the cylinder body 20B. Therefore, when the temperature of the coolant is in the high temperature region, the temperature of the cylinder body 20B of the engine unit 11 which is a long stroke engine unit can be sufficiently lowered by the coolant. As a result, it is possible to suppress heat exchange between the intake air and the cylinder bore 20Ba during the intake stroke and reduce the amount of temperature rise of the intake air. Therefore, knocking is unlikely to occur in the engine unit 11 which is a long stroke engine unit.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and specific examples thereof, and various modifications can be made as long as they are described in the claims. Hereinafter, an example of modification of the embodiment of the present invention will be described.

The engine unit of the present invention may include a coolant pump device that is not an electric coolant pump device. This coolant pump device may be a mechanical coolant pump device operated by the rotational force of the crankshaft. The mechanical coolant pump device may be connected to a camshaft. The mechanical pump device connected to the camshaft operates by the rotational force of the camshaft when the camshaft rotates in conjunction with the rotation of the crankshaft. The mechanical coolant pump device may be connected to the crankshaft. The mechanical coolant pump device may be connected to a rotatable shaft that is different from the crankshaft and camshaft.

The coolant pump device of the present invention may be a magnet-driven pump device. In the magnet-driven pump device, the pump is provided with a permanent magnet. This permanent magnet exerts a magnetic force on a shaft made of a rotatable magnetic material. For example, assume that the permanent magnet is fixed to the impeller of the pump and the shaft is a camshaft. In this case, when the camshaft rotates, the impeller rotates together with the camshaft due to the magnetic force generated by the permanent magnet.

The coolant pump device of the present invention may be provided at a portion different from the crankcase of the engine body. For example, the coolant pump device of the present invention may be provided on the cylinder body.

The diameter of the cylinder bore of the engine unit, which is the single-cylinder engine unit of the present invention, may be larger than the stroke of the piston. That is, the single-cylinder engine unit of the present invention may be a short stroke engine unit.

The engine unit of the present invention may have a plurality of intake ports for one combustion chamber. The engine unit of the present invention may have a plurality of exhaust ports for one combustion chamber.

The engine unit of the present invention may be a multi-cylinder engine unit having a plurality of cylinder bores. In this case, the diameter of all the cylinder bores may be the first diameter, and the stroke of all the pistons reciprocating in each cylinder bore may be the first stroke longer than the first diameter. Further, in this case, the diameter of a part of the cylinder bores may be the first diameter, and the stroke of the piston reciprocating in each cylinder bore having the first diameter may be the first stroke longer than the first diameter. Further, in this case, the diameters of all the cylinder bores may be larger than the stroke of the piston reciprocating in each cylinder bore.

When the engine unit of the present invention is a multi-cylinder engine unit, or when the engine unit of the present invention has a plurality of intake ports for one combustion chamber, the engine unit is connected to a plurality of intake ports, respectively. First intake passage section, a plurality of branch intake passage sections connected to the upstream ends of the plurality of first intake passage sections, and one collective intake passage section connected to the upstream ends of the plurality of branch intake passage sections. May have. The second intake passage portion has a plurality of branch intake passage portions and a surge tank. The throttle valve may be arranged inside each branch intake passage portion. The throttle valve may be arranged in the collective intake passage portion. In this case, the throttle valve is arranged in the surge tank of the collective intake passage portion. The throttle valve does not have to be located in the surge tank.

When the engine unit of the present invention is a multi-cylinder engine unit, or when the engine unit of the present invention has a plurality of intake ports for one combustion chamber, the first intake passage portion is connected to each of the plurality of intake ports. It may have a plurality of branched intake passages and one collective intake passage connected to the upstream end of the plurality of branched intake passages.

When the engine unit of the present invention is a multi-cylinder engine unit, or when the engine unit of the present invention has a plurality of exhaust ports for one combustion chamber, the engine unit is connected to a plurality of exhaust ports, respectively. A first exhaust passage portion and a plurality of second exhaust passage portions connected to each of the downstream ends of the plurality of first exhaust passage portions may be provided.

When the engine unit of the present invention is a multi-cylinder engine unit, or when the engine unit of the present invention has a plurality of exhaust ports for one combustion chamber, the first exhaust passage portion is connected to each of the plurality of exhaust ports. It may have a plurality of independent exhaust passages and one collective exhaust passage connected to the downstream end of the plurality of independent exhaust passages.

The engine unit of the present invention may be a direct injection engine unit. The direct injection engine unit is a type of engine unit in which fuel is injected in the combustion chamber. The engine unit of the present invention may be a two-stroke engine unit. The engine unit of the present invention may be a diesel engine unit. Diesel engine units do not have spark plugs. The engine unit of the present invention may be a supercharged engine provided with a supercharger. A turbocharger is a device that compresses the air supplied to the combustion chamber. The supercharger may be a mechanical supercharger or an exhaust turbine type supercharger (so-called turbocharger).

The engine unit of the present invention may be provided inside a cylinder head or a cylinder body and may be provided with a switching valve provided in a coolant passage portion.

The switching valve of the present invention does not have to be a thermostatic valve. For example, the switching valve may be a solenoid valve or an electric valve having a movable valve body that can move between a low temperature position and a high temperature position according to the temperature of the coolant detected by the coolant temperature sensor.

The switching valve of the present invention does not have to be a four-way valve. For example, the switching valve of the present invention may be a three-way valve, and a plurality of three-way valves may be provided in the coolant passage portion. Also in this case, when the temperature of the coolant is in the first low temperature region, the coolant does not pass through the radiator and the cylinder body, but in the coolant pump device, the cylinder head, and the coolant pump device in this order. To circulate. Further, when the temperature of the coolant is in the high temperature region, the coolant is circulated in the coolant passage portion in the order of the coolant pump device, the cylinder head, the radiator, the cylinder body, and the coolant pump device.

The engine unit of the present invention does not have to be provided with a bypass passage portion.

When the engine unit of the present invention is mounted on a vehicle, the rotation center axis of the crankshaft of the engine unit is not limited to being parallel to the left-right direction of the vehicle. For example, the rotation center axis of the crankshaft may be parallel to the vehicle front-rear direction.
When the engine unit of the present invention is mounted on a vehicle, the direction of the cylinder axis, which is the central axis of the cylinder bore of the engine body, is not limited to the direction of the specific example. When the engine unit is viewed in the left-right direction of the vehicle, the cylinder axis may be parallel to the vertical direction of the vehicle. When the engine unit is viewed in the left-right direction of the vehicle, the inclination angle of the cylinder axis with respect to the vertical direction may be larger than 45 ° and 90 ° or less.

The vehicle on which the engine unit of the present invention is mounted is not limited to a motorcycle. The present invention may be mounted on a saddle-mounted vehicle other than a motorcycle. A saddle-mounted vehicle refers to a vehicle in which an occupant straddles a saddle. The saddle-mounted vehicle on which the engine unit of the present invention is mounted includes, for example, a motorcycle, a three-wheeled vehicle, a four-wheeled buggy (ATV: All Terrain Vehicle), a watercraft, a snowmobile, and the like. Examples of motorcycles include scooter type, off-road type, moped type and the like. The engine unit of the present invention may be mounted on a vehicle other than a saddle-mounted vehicle. For example, the engine unit of the present invention may be mounted on a four-wheeled vehicle (automobile) or a ship that is not a saddle-type vehicle. The vehicle to which the present invention is applied may be a hybrid vehicle having an engine unit and an electric motor as a drive source. Further, the engine unit of the present invention may be mounted on a device other than the vehicle.

11 Engine unit 20 Engine body 20A Crankcase 20Ba Crankbore 20Ba
20C Cylinder Head 20Ca Cylinder Head Intake Passage (1st Intake Passage)
20Cb Cylinder head exhaust passage (first exhaust passage)
20X Cylinder axis 22 Piston 41 Coolant passage 41g Bypass passage 42 Coolant pump device (electric coolant pump device)
43 Switching valve 43b1 First inlet 43b2 Second inlet 43c1 First outlet 43c2 Second outlet 43d Movable valve body 44 Radiator 51 External intake passage (second intake passage)
61 External exhaust passage (second exhaust passage)
St 1st stroke Db 1st diameter

Claims (12)

A cylinder body in which at least one cylinder bore is formed, and
With the cylinder head connected to the cylinder body,
A coolant passage portion in which at least a part of the coolant passes through the cylinder head and the cylinder body and the coolant circulates inside.
A coolant pump device provided in the coolant passage portion and pumping the coolant to circulate the coolant in the coolant passage portion.
The radiator provided in the coolant passage portion and
Equipped with
When the temperature of the coolant is in the first low temperature region, the coolant pump device, the cylinder head, and the coolant pump device are passed through the coolant passage portion in this order without passing through the radiator and the cylinder body. The coolant flows,
When the temperature of the coolant is in the high temperature region higher than the first low temperature region, the coolant pump device, the cylinder head, the radiator, the cylinder body, and the coolant pump device are in this order in the coolant passage portion. The engine unit is configured to allow the coolant to flow. When the temperature of the coolant is in the first low temperature region, the coolant pump device, the cylinder head, and the coolant pump device are in this order in the coolant passage portion without passing through the radiator and the cylinder body. When the first state allows the coolant to flow and the temperature of the coolant is in the high temperature region, the coolant pump device, the cylinder head, the radiator, the cylinder body, and the cooling A claim characterized in that a switching valve configured to be in a second state for allowing the coolant to flow in the coolant passage in the order of the liquid pump device is provided in the coolant passage. Item 1. The engine unit according to Item 1. The switching valve
A first inlet into which the coolant flowing out of the cylinder head flows in, a first outlet allowing the coolant to flow out toward the radiator, and a second inlet in which the coolant flowing out of the cylinder body flows in. , And a second outlet that allows the coolant to flow out towards the coolant pump device.
The four-way valve
The first, which prevents the coolant flowing into the first inlet from flowing out from the second outlet and preventing the coolant flowing into the second inlet from flowing out from the first outlet and the second outlet. 1 state and
The second state in which the cooling liquid flowing into the first inlet flows out from the first outlet and the cooling liquid flowing into the second inlet flows out from the second outlet.
It is configured to be switched to
When the temperature of the coolant is in the first low temperature region, the four-way valve is in the first state, so that the coolant pump device and the cylinder head do not pass through the radiator and the cylinder body. , The four-way valve, and the coolant pump device in this order, the coolant circulates in the coolant passage portion.
When the temperature of the coolant is in the high temperature region, the four-way valve is in the second state, so that the coolant pump device, the cylinder head, the four-way valve, the radiator, the cylinder body, and the like. The engine unit according to claim 2, wherein the coolant circulates in the coolant passage portion in the order of the four-way valve and the coolant pump device. The engine unit according to claim 2 or 3, wherein the switching valve is located outside the cylinder head and the cylinder body, and is separate from the cylinder head and the cylinder body. When the switching valve is in the first state, at least one of the coolant and air flows into the coolant passage portion formed in the cylinder body via the radiator.
The invention according to any one of claims 2 to 4, wherein the cylinder body has a bypass passage portion connected to the coolant passage portion and the cylinder head has a bypass passage portion connected to the coolant passage portion. Engine unit. The engine unit has a crankshaft and
The one according to any one of claims 1 to 5, wherein the coolant pump device is configured to be switched between a stopped state and an operating state independently of the movement of the crankshaft. Engine unit. The engine unit according to claim 6, wherein the coolant pump device is configured to be in the stopped state when the temperature of the coolant is in the second low temperature region lower than the first low temperature region. .. The engine unit has at least one piston that reciprocates within the at least one cylinder bore along a cylinder axis that is the central axis of the cylinder bore.
The diameter of the at least one cylinder bore is the first diameter.
The engine unit according to any one of claims 1 to 7, wherein the stroke of the piston reciprocating in the cylinder bore having the first diameter is a first stroke longer than the first diameter. .. The engine unit
A combustion chamber with an intake port and
A first intake passage portion formed in the cylinder head and connected to the intake port,
A second intake passage portion arranged outside the cylinder head, which is connected to the upstream end of the first intake passage portion in the air flow direction and has a throttle valve arranged therein.
A fuel injection device that injects fuel in the first intake passage portion or the second intake passage portion.
The engine unit according to any one of claims 1 to 8, wherein the engine unit has. The engine unit
The engine unit according to claim 9, further comprising an ignition plug that ignites a mixture of air and fuel in the combustion chamber. The cylinder axis, which is the central axis of the cylinder bore, is inclined with respect to the vertical direction of the vehicle on which the engine unit is mounted.
The engine unit
A combustion chamber with an exhaust port and
A first exhaust passage portion formed in the cylinder head and connected to the exhaust port, and
A second exhaust passage portion arranged outside the cylinder head, which is connected to the downstream end of the first exhaust passage portion in the gas flow direction, and a second exhaust passage portion.
Have,
A claim characterized in that, when the vertical direction of the vehicle on which the engine unit is mounted is the vertical direction, the downstream end of the first exhaust passage portion is formed on the downward outer surface of the cylinder head. Item 6. The engine unit according to any one of Items 1 to 10. The engine unit according to any one of claims 1 to 11, wherein only one cylinder bore is formed in the cylinder body.

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