Prime mover and working machine having the same

A prime mover includes an engine, a fan to generate a cooling airflow around the engine, an air-intake tube to supply outside air to the engine, a connection tube to supply, to the air-intake tube, a blow-by gas generated in the engine, and a wind shielding member to shield the connection tube from the cooling airflow, the wind shielding member being arranged around the connection tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2018-076753, filed Apr. 12, 2018. The content of this application is incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a prime mover having a connection tube in which a blow-by gas generated by the prime mover flows toward an air-intake tube.

Discussion of the Background

A prime mover disclosed in Japanese Patent Application Publication No. 2017-141770 is previously known as a prime mover having a blow-by gas recirculation structure in which the blow-by gas (air-fuel mixture or combustion gas leaked into the engine housing from the gap between the piston and cylinder of the prime mover) is supplied to the intake tube and then re-combusted.

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, in the prime mover disclosed in Japanese Patent Application Publication No. 2017-141770, the blow-by gas flowing through the inside of the connection tube is cooled when the working machine such as a tractor provided with the prime mover is used under the low temperature conditions such as a cold region, and then liquids such as the oil (engine oil) and water included in the blow-by gas may freeze and the connection tube may be clogged in the middle of the connection tube.

The present invention is provided to solve the problems of the conventional technique mentioned above, and intends to suppress, inside the connection tube, freezing of the liquid included in the blow-by gas.

Means of Solving the Problems

A prime mover according to one aspect of the present invention, includes an engine, a fan to generate a cooling airflow around the engine, an air-intake tube to supply outside air to the engine, a connection tube to supply, to the air-intake tube, a blow-by gas generated in the engine, and a wind shielding member to shield the connection tube from the cooling airflow, the wind shielding member being arranged around the connection tube.

Effects of the Invention

According to the above-mentioned prime mover and a working machine provided with the prime mover, it is possible to prevent a cooling airflow generated by the fan from being directly blown to the connection tube, and thereby the freezing of the liquid included in the blow-by gas can be suppressed inside the connection tube.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described below with reference to the drawings as appropriate.

FIG. 13is a schematic view showing an overall configuration of a working machine1according to the embodiment of the present invention. In the present embodiment, an articulated wheel loader is illustrated as the working machine1. However, the application object of the present invention is not limited to the articulated wheel loader, and can be applied to the agricultural machines such as a tractor, the construction machines such as a backhoe, various types of vehicles, and the like.

The working machine1includes a traveling machine body4, a working device6, and a cabin8.

Hereinafter, in the explanation of the embodiment, the front side (the left side inFIG. 13) of an operator seated on the operator seat9of the cabin8is referred to as the front. The rear side (the right side inFIG. 13) of the operator is referred to as the rear. The left side (the front surface side ofFIG. 13) of the operator is referred to as the left. The right side (the back surface side ofFIG. 13) of the operator is referred to as the right. In addition, a horizontal direction which is a direction orthogonal to the front-rear direction (see the arrowed line K1inFIG. 13) will be described as a machine width direction.

As shown inFIG. 13, the traveling machine body4has a front machine body4aand a rear machine body4b. The front machine body4ais provided with a pair of front wheels5a(a right front wheel5aand a left front wheel5a). The rear machine body4bis provided with a pair of rear wheels5b(a right rear wheel5band a left rear wheel5b).

On the front end side of the rear machine body4b, a coupling member11is provided rotatably about an axis extending along the front-rear direction. The rear end side of the front machine body4ais connected to the coupling member11so as to be able to swing leftward and rightward around an axis extending along the vertical direction.

The working device6has a pair of lift arms12and a bucket14. The lift arms12are arranged to face each other in the machine width direction. The base end sides of the pair of lift arms12are supported by the support frame13rotatably about the axis of the pivot shaft13aextending in the left-right direction, the support frame13being provided on the front machine body4a, and thus the pair of lift arms12can be moved upward and downward.

The bucket14is pivotally connected to the tip end sides of the pair of lift arms12so as to be swingable about the axial center of a pivot shaft14aextending in the lateral direction. The pair of lift arms12are driven by a lift cylinder15. The bucket is driven by a bucket cylinder16. The lift cylinder15and the bucket cylinder16are constituted of hydraulic actuators, that is, constituted of hydraulic cylinders more specifically.

In addition, the bucket14is detachably provided. Instead of the bucket14, an attachment such as a sweeper, a mower, and a breaker can be attached to the tip end sides of the lift arms12.

The rear machine body4bis provided with the operator seat9, the cabin8serving as an operator seat protection device, a steering wheel (not shown in the drawings) for operating the steering cylinder, and a working device operation lever (not shown in the drawings) for operating the working device6.

As shown inFIG. 13, the rear body4bis provided with a prime mover room ER. In the prime mover room ER, a prime mover10, a hydraulic pump18, an intercooler23, a radiator24, an air cleaner24, and the like are arranged.

The prime mover10is an engine in the present embodiment, that is, the prime mover10is a diesel engine more specifically. As shown inFIG. 13, the prime mover10is arranged in a longitudinal direction such that the output shaft10ais directed in the front-rear direction.

Next, the prime mover10will be explained in detail mainly referring toFIG. 1toFIG. 3andFIG. 8. In each of the drawings, an arrowed line A1indicates the front, an arrowed line A2indicates the rear, an arrowed line B1indicates the left, and an arrowed line B2indicates the right.

FIG. 2is a front view showing the prime mover10, the hydraulic pump18, the intercooler23, and the like.FIG. 3is a right side view showing the prime mover10, the fan21, the hydraulic pump18and the like.FIG. 8is a back view showing the wind shielding plate40, the fan21and the like.

As shown inFIG. 1toFIG. 3andFIG. 8, the prime mover10includes a cylinder block20a, a cylinder head20b, a cylinder head cover20c, and an oil pan20d. The cylinder block20aincludes a cylinder portion and a crankcase. A plurality of pistons are housed in the cylinder portion.

The plurality of pistons reciprocate inside the cylinder portion to perform suction, compression, expansion, and exhaust. The crankcase houses a crankshaft. The crankshaft converts the reciprocating motions of the plurality of pistons into the rotational motion. The cylinder head20bis provided on an upper portion of the cylinder block20a.

In the cylinder head20b, an ignition plug, a cam shaft and the like are housed. The cylinder head cover20cis provided on an upper portion of the cylinder head20b. The cylinder head cover20cis a cover that covers over the cylinder head20b. The oil pan20dis provided on a lower portion of the cylinder block20a. The oil pan20dprevents the outflow of the oil (engine oil) of the prime mover10.

In the following description, a component including the cylinder block20a, the cylinder head20b, and the cylinder head cover20cis referred to as an engine housing20. The output shaft10ais arranged, inside the engine housing20, extending in the front-rear direction.

As shown inFIG. 3and the like, the hydraulic pump18is provided in front of the prime mover10. The hydraulic pump18is driven by the prime mover10. The hydraulic pump18outputs an operation fluid for operating the hydraulic actuators such as the steering cylinder, the lift cylinder15, and the bucket cylinder16provided in the working machine1.

As shown inFIG. 3, a fan21is provided behind the prime mover10. The fan21is attached rotatably and integrally with the rear portion of the output shaft10a. The fan21is rotationally driven by the power of the prime mover10to generate a cooling airflow.

In particular, the fan21generates the cooling airflow flowing from the front to the rear in the present embodiment. That is, the fan21generates the cooling airflow around the prime mover (engine)10.

As shown inFIG. 1andFIG. 2, a supercharger22is arranged above the right portion of the prime mover10. When the turbine inside the supercharger22is rotated by the exhaust gas discharged from the prime mover10, the supercharger22supplies, to the prime mover10, the air compressed by the compressor of the supercharger22.

The intercooler23is a cooler configured to cool the compressed air that will be supplied from the compressor side of the supercharger22to the prime mover10. In particular, the intercooler23cools the air introduced from the supercharger22. As shown inFIG. 1, the intercooler23is arranged behind the fan22.

The radiator24is arranged behind the intercooler23, and is cooled by the cooling airflow generated by the fan21. The radiator24cools the cooling water that will be supplied to the prime mover10.

The air cleaner25is provided on the left side of the rear upper portion of the prime mover10. The air cleaner25removes foreign substances such as the dust and the dirt that are contained in the air sucked from the outside. The air cleaner25has the first side surface25aformed in a substantially cylindrical shape and the second side surface25cformed in a substantially cylindrical shape. In the air cleaner25, the length of the cylindrical portion25bin the front-rear direction is longer than the diameters of the first side surface25aand the second side surface25c.

The prime mover10is provided with an air intake tube35. The air intake tube35is connected to the engine housing20, and supplies the air from the outside of the engine housing20to the inside of the engine housing20. That is, the air intake tube35supplies the outside air to the prime mover (engine)10.

As shown inFIG. 1,FIG. 2, and the like, the air intake tube35is arranged above the engine housing20. One end side of the air intake tube35is connected to the inside of the engine housing20. In particular, one end side of the air intake tube35is connected to the inside of the cylinder head20b. An air cleaner25is connected to the other end side of the air intake tube35.

The air intake tube35includes a first air intake tube35a, a second air intake tube35b, a first cooling tube35c, and a second cooling tube35d. The first air intake tube35a, the second air intake tube35b, the first cooling tube35c, and the second cooling tube35dare each constituted of hollow tubes, for example, hoses or pipes.

As shown inFIG. 4, the first air intake tube35acommunicates the air cleaner25and the second air intake tube35bwith each other.

The second air intake tube35bcommunicates the outlet of the first air intake tube35awith the inlet22aof the supercharger22, the inlet22abeing arranged on the compressor side.

The first cooling tube35ccommunicates the inlet23aof the intercooler with the outlet22bof the supercharger22, the outlet22bbeing arranged on the compressor side.

The second cooling tube35dcommunicates the outlet23bof the intercooler with the inside of the engine housing20. In particular, the second cooling tube35dis connected to an intake manifold arranged in the cylinder head20b.

As shown inFIG. 4, the prime mover10includes a blow-by gas recirculation structure30. As shown inFIG. 4, the blow-by gas recirculation structure30is configured to supply the blow-by gas (the mixture gas and the combustion gas leaking from the gap between the piston and the cylinder of the prime mover10into the engine housing20) into a cylinder formed in the engine housing20with the intake air flow, and then to re combust the blow-by gas.

The blow-by gas recirculation structure30has a blow-by gas path. The blow-by gas path is formed in the engine housing20. The blow-by gas path allows the blow-by gas generated in the engine housing (crankcase)20to flow from the inside of the cylinder head cover20cto the outside.

As shown inFIG. 4, the blow-by gas recirculation structure30includes a connection tube37connected to the cylinder head cover20c. For example, a PCV valve is provided on the upper portion of the cylinder head cover20c, and an outlet36for the blow-by gas is formed in the PCV valve.

The PCV valve controls the amount of the blow-by gas that will be recirculated when the blow-by gas is sent to the cylinder together with the intake air for re-combustion. The PCV valve may be provided at the joining position between the connection tube37and the air intake tube35.

The cylinder head cover20cis in communication with the oil separator26with the connection tube37. The oil separator26is provided leftward on the upper portion of the prime mover10. The oil separator26is attached to the prime mover10with an attachment bracket (not shown in the drawings). The oil separator26separates the mist of engine oil mixed with the blow-by gas from the blow-by gas.

The oil return passage26aextends from the lower portion of the oil separator26, and is in communication with the inside of the engine housing (crank case)20. The engine oil separated from the blow-by gas by the filter (the oil separator)26returns to the inside of the engine housing20through the oil return path26aby the gravity fall. The oil separator26is covered with a heat insulating material.

The connection tube37communicates the cylinder head cover20c(PCV valve) and the oil separator26with each other, and is connected to the air intake tube35. The connection tube37recirculates the blow-by gas generated in the prime mover (engine)10to the air intake tube35.

As shown inFIG. 1, the connection tube37is arranged extending above the engine10. The connection tube37is, for example, constituted of a hollow tube such as a pipe or a hose. The outer circumference of the connection tube37is covered with a heat insulating material. The connection tube37includes a first connection tube37aand a second connection tube37b.

As shown inFIG. 5, the first connection tube37ahas a first portion37a1extending backward from the connection portion36of the cylinder head cover20c, a second portion37a2extending leftward from the end portion of the first portion37a1, a third portion37a3extending forward from the end portion of the second portion37a2above the left end portion of the engine housing20, and fourth portion37a4extending downward from the end portion of the third portion37a3and being connected to the oil separator26.

In addition, the second portion37a2includes an upstream side portion extending obliquely upward from the first portion37a1side to the third portion37a3side, a middle portion curved from the upstream side portion and extending obliquely downward toward the third portion37a3side, and a downstream side portion curved from the left end portion of the middle portion and extending substantially horizontally toward the third portion37a3.

In addition, the second portion (flow path intersecting portion)37a2is arranged at a position intersecting with the flow path of the cooling airflow generated by the fan21(in the embodiment, a position substantially orthogonal to the flow path). Meanwhile, the downstream side portion of the first connection tube37ais orthogonal to the second cooling tube35dwhen viewed from above.

The prime mover10is provided with a wind shielding plate (wind shielding member)40which shields a part of the connection tube37(a flow path intersecting portion37a2intersecting with the flow path of the cooling airflow generated by the fan21) from the cooling airflow.

FIG. 5is an exploded perspective view of the wind shielding plate40viewed from the left front.FIG. 6is a right-rear perspective view showing the back surface of the wind shielding plate40.FIG. 7is a left-front perspective view showing the bracket50.

InFIG. 11A, the front surface side of the sheet indicates the rear, the back surface side of the sheet indicates the front, the arrowed line B1indicates the left, and the arrowed line B2indicates the right.FIG. 11Bis a left side view showing the positions of the wind shielding plate40and the connection tube37.

The wind shielding plate40is arranged around the connection tube37(radially outward). The wind shielding plate40is arranged to face at least a portion of the second portion37a2of the connection tube37, the portion being adjacent to a portion connecting to the first portion37a1, and thereby the portion is shielded from the cooling airflow.

In particular, the wind shielding plate40is arranged to face the upstream side portion and the middle portion of the second portion37a2in the present embodiment. The wind shielding plate40is provided on the prime mover10by the bracket50. The wind shielding plate40includes a first plate portion41and a second plate portion42.

The first plate portion41is arranged in front of the connection tube37. The first plate portion41is arranged directing one surface of the first plate portion41forward and directing the other surface faces backward. In addition, the first plate portion41is arranged on the upstream side of the flow direction of the cooling airflow generated by the fan21.

A through hole41bis formed in the first plate portion41, and a nut41chaving a screw hole communicated with the through hole41bis attached to the first plate portion41. The nut41cis fixed to the rear side of the first plate portion41by the welding or the like. The first plate portion41is attached to the bracket50with a bolt41ainserted into the nut41c.

As shown inFIG. 11AandFIG. 11B, the first plate portion41includes a portion (first wall portion)41A located on the right side and a portion (second wall portion)41B located on the left side. The upper end portion of the first wall portion41A is inclined downwardly rightward. A notch41A1having a substantially arc-shape is formed on the right lower end portion of the first wall41A. The upper end portion of the second wall portion41B is inclined downwardly leftward.

As shown inFIG. 5,FIG. 6, and the like, the second plate portion42is arranged extending backward from the upper portion of the first board part41. The second plate portion42is arranged extending toward the downstream side of the flow direction of the cooling airflow generated by the fan21. The second plate portion42is arranged above the connection tube37. The second plate portion42includes a first portion42A and a second portion42B.

The first portion42A is arranged extending backward from the right upper portion of the first plate portion41. In particular, the first portion42A is formed by bending the upper end portion of the first wall portion41A.

The second portion42B is arranged extending backward from the left upper portion of the first plate portion41. In particular, the second portion42B is formed by bending the upper end portion of the second wall portion41B. A notch42having a substantially arc-shape is formed at the right rear portion of the second plate portion42. The second plate portion42is formed such that the end portion of the first portion42A and the end portion of the second portion42B are adjacent or contacted to each other at the opposed portion42C.

As shown inFIG. 11A, the first portion42A and the second portion42B are formed in a shape corresponding to the curved shape of the connection tube37so that the clearance from the upper surface of the connection tube37is substantially constant.

As shown inFIG. 1, the bracket50is attached to the rear upper portion of the cylinder head cover20c. The wind shielding plate40is attached to the bracket50. In particular, as shown inFIG. 5, the bracket50is attached by screwing a bolt51ainto a screw hole51cformed in the rear upper portion of the cylinder head cover20c.

As shown inFIG. 5andFIG. 7, the bracket50has a first supporting portion51and a second supporting portion52. The first supporting portion51is provided with a through hole51bthrough which the bolt51ais inserted. In the present embodiment, the first supporting portion51has a length in the front-rear direction longer than a length in the left-right direction. In addition, two through holes51bare formed at intervals in the front-rear direction.

As shown inFIG. 5, the second supporting portion52is arranged extending upward from the upper surface of the first supporting portion51. The second supporting portion52includes a vertical portion53and a fixing portion54.

The vertical portion53stands upward from the upper surface of the first supporting portion51. The vertical portion53has a rectangular shape whose length in the vertical direction is longer than the length in the front-rear direction. The vertical portion53is arranged to direct one surface leftward and direct the other surface faces rightward.

The fixing portion54is a portion to which the first plate portion41of the wind shielding plate40is attached. The fixing portion54is arranged extending leftward from the left upper portion of the vertical portion53. The fixing portion54has an inverted L-shape having the upper portion extending, leftward, and is arranged to direct one surface forward and direct the other surface backward.

In the upper portion of the fixing portion54, two through holes54apenetrating in the front-rear direction are formed at intervals in the machine width direction. When the bolt41aof the first plate portion41is inserted to the through hole54aof the fixing portion54and then the bolt41ais tightened, the wind shielding plate40can be attached to the bracket50.

The bracket50also has a clamp member55. In particular, the clamp member55is provided at the rear portion of the first supporting portion51. The clamp member55clamps the connection tube37. To explain in detail, the clamp member55has a holding portion56and a vertical portion57.

The vertical portion57is arranged extending upward from the rear portion of the first plate portion41. The vertical portion57is arranged with one surface directed forward and the other surface directed backward. A holding portion56is arranged at the upper end portion of the vertical portion57. The holding portion56has a substantially P-shape in the side view.

By tightening the bolt56a, the inner diameter of the holding portion56is reduced, and thus the holding portion56claims the connection tube37. In addition, the structure of the holding part56is not limited to the above-mentioned structure, and any structure for clamping the connection37may be employed.

In the present embodiment, the wind shielding plate40is formed by bending a plate material such as metal. However, the material is not limited to that, and the wind shielding plate40may be formed of resin or the like. Moreover, the shape of the wind shielding plate40is not limited to the above-mentioned shape, and a shape as shown inFIG. 12may be employed, for example.

FIG. 12is a perspective view showing a left front portion of a wind shielding plate140that is a modified example of the wind shielding plate40. As shown inFIG. 12, the wind shielding plate140has a first plate portion141, a second plate portion142, and an extended portion143.

The first plate portion141is arranged in front of the connection tube37. The first plate portion141has, for example, a substantially rectangular shape having the length in the left-right direction longer than the length in the vertical direction. The first plate portion41is attached to the bracket50with a bolt141a.

Describing in detail, a boss141bhaving a cylindrical shape protruding forward as shown inFIG. 12is formed at the lower portion of the first plate portion14. Two bosses141bare formed at intervals in the machine width direction.

Inside the boss141b, a nut (not shown in the drawings) whose axial direction is directed in the front-rear direction is molded in an inserted manner. The first plate portion141is fixed to the bracket50with the nut, the boss141b, and the bolt141a.

As shown inFIG. 12, the second plate portion142is arranged backwardly upward from the first plate portion141. The second plate portion142and the first plate portion141are coupled with each other by the extended portion143. The second plate portion142is arranged above the connection tube37. The second plate portion142has a substantially rectangular shape in which the length in the left-right direction is longer than the length in the front-rear direction. A notch142ahaving an arcuate shape is formed at the right rear portion of the second plate portion142.

The extended portion143is arranged extending from the first plate portion141and connected to the second plate portion142. In particular, the extended portion143is arranged extending from the upper end portion of the first plate portion141to the front end portion of the second plate portion142, and extends so as to draw an arc in the side view.

As in the present embodiment, the wind shielding plate40covers not only a part of the connection tube37but the whole of the connection tube37. In the present embodiment, the configuration where the wind shielding plate40is attached to the bracket50by a bolt. However, the configuration is not limited to that configuration, and the wind shielding plate40may be attached by the welding or the like.

Hereinafter, the wind shielding plate40will be described in detail with reference toFIG. 1,FIG. 8,FIG. 11A, andFIG. 11B.FIG. 8is a back view illustrating the wind shielding plate40, the fan21and the like.

As shown inFIG. 8, the wind shielding plate40is arranged above the engine housing20as viewed from the front or the rear (in a direction parallel to the rotation axis of the fan21), and is overlapped with at least the rotation track R1of the fan21.

In particular, the upper end of the rotation track RI of the fan21is higher than the upper end of the engine housing20, and is arranged at a height between the upper end of the first plate portion41and the lower end.

As shown inFIG. 11A, the lower end portion (lower end portion of the first plate portion41other than the notch41A1)41C of the wind shielding plate40is located below the lower portion37A of the connection tube37. Describing in detail, the right portion41C1of the lower end portion41C of the wind shielding plate40is arranged at a position lower than the right portion37A1of the lower portion37A of the connection tube37by a predetermined distance in the back view.

In addition, the left portion41C2of the lower end portion41C of the wind shielding plate40is arranged at a position lower than the left portion37A2of the lower portion37A of the connection tube37by a predetermined distance in the back view. The left portion41C2and the left portion37A2are substantially parallel to each other.

Further, the wind shielding plate40and the connection tube37are separated from each other by a predetermined distance in the vertical direction. That is, a space portion E1is formed between the second plate portion42of the wind shielding plate40and the outer circumferential surface of the connection tube37. Describing the space E1in detail, the space portion E1includes a space formed between the first portion42A and the right portion37B1of the upper portion37B of the connection tube37, and a space formed between the second portion42B and the left portion37B2of the upper portion37B of the connection tube37.

The first portion42A and the right portion37B1are separated from each other by a predetermined distance in the vertical direction, and are substantially parallel to each other. The second portion42B and the left portion37B2are separated from each other by a predetermined distance in the vertical direction, and are substantially parallel to each other.

As shown inFIG. 11B, the length L1of the wind shielding plate40in the front-rear direction, that is, the length L1of the second plate portion42in the front-rear direction is longer than the outer diameter L2of the connection tube37. In addition, the connection tube37is arranged immediately below the second plate portion42, and the connection tube37is positioned within the width of the second plate portion42in the front-rear direction.

That is, the connection tube37is arranged forward from the rear end42B1of the second plate portion42. In addition, the wind shielding plate40and the connection tube37are separated from each other by a predetermined distance in the front-rear direction. That is, a space portion E2is also formed between the first plate portion41of the wind shielding plate40and the outer circumferential surface of the connection tube37.

As shown inFIG. 1andFIG. 2, a first cooling tube35cextends in the front-rear direction on the right side of the wind shielding plate40. In addition, a second cooling tube35dextends in the front-rear direction on the left side of the wind shielding plate40. In other words, the wind shielding plate40is arranged between the first cooling tube35cand the second cooling tube35d.

Hereinafter, the flow (air flow) of the cooling airflow in the prime mover room ER will be described.

FIG. 9is a left front perspective view showing the left front portion of the prime mover10, the flow of cooling airflow, and the like.FIG. 10is a right side view showing the prime mover10, the flow of cooling airflow, and the like.

As shown inFIG. 10, the fan21generates a cooling airflow W1that travels from the front to the rear in the prime mover room ER. As shown inFIG. 9andFIG. 10, the cooling airflow generated by the fan21flows toward the connection tube37in the prime mover room ER as indicated by the air flow W2.

The cooling airflow W2that has flown toward the connection tube37hits the wind shielding plate40, and then diffuses outward in the surface direction of the wind shielding plate40(for example, in the vertical direction and in the machine width direction) as shown in the air flow W3.

That is, the wind shielding plate40shields a part of the second portion37a2(the flow path intersecting portion37a2intersecting the flow path of the cooling airflow) of the connection tube37from the cooling airflow, and thus the cooling airflow flowing toward the connection tube37can be prevented from directly hitting the connection tube37.

The cooling airflow diffused to the upper side of the wind shielding plate40is introduced backward from the connection tube37by the second plate portion42. Thus, the wind shielding plate40arranged in front of the connection tube37shields the connection tube37from the cooling airflow.

Hereinafter, the operation of the blow-by gas recirculation structure30will be described with reference toFIG. 4. When the fuel is combusted in the combustion chamber34of the engine housing20, the blow-by gas leaks from the gap between the cylinder and the piston ring due to the rapid pressure increase and flows into the engine housing (crankcase)20.

The blow-by gas comes into contact with the engine oil adhering to the inner circumferential surface of the cylinder when passing through the gap, and absorbs (includes) the misty engine oil. The blow-by gas flows from the cylinder head cover20cinto the oil separator26through the first connection tube37a.

When the blow-by gas passes through the first connection tube37a, the cooling airflow flows toward the first connection tube37a(from the front toward the rear). However, in the present embodiment, the wind shielding plate40shields the first connection tube37afrom the cooling airflow.

For this reason, even under a cryogenic condition such as a cold area, it is possible to suppress that the blow-by gas is cooled inside the connection tube37and the liquid such as oil or water contained in the blow-by gas is frozen. In this manner, the liquid in the blow-by gas can be prevented from freezing inside the connection tube37, and the inside of the connection tube37can be prevented from being clogged. As the result, the pressure in the engine housing20can be prevented from increasing, and thus it is possible to avoid the oil leakage and the like.

In addition, the wind shielding plate40is arranged closer to the connection portion36than at least at a middle portion between the connection portion36of the connection tube37with the engine housing20and the connection portion with the oil separator26. In this manner, the blow-by gas can flow into the intake tube35through a region intersecting with the flow path of the cooling airflow in the connection tube37while keeping the temperature of the blow-by gas to a temperature relatively close to the temperature of the connection portion36.

The oil separator26separates the engine oil contained in the blow-by gas. The engine oil captured by the filter (the oil separator)26passes through the oil return path26adue to the gravity fall and returns to the inside of the engine housing20.

When flowing out from the oil separator26, the blow-by gas from which the engine oil has been removed flows into the second air intake tube35bthrough the second connection tube37b. In this manner, the blow-by gas merges with the air taken in from the air cleaner25, and flows into the inlet22aof the supercharger22on the compressor side.

The supercharger22rotates the turbine with use of the exhaust from the prime mover10to compress the air on the compressor side. The air compressed by the compressor of the supercharger22(the mixture of the air taken in from the outside air and the blow-by gas) flows from the outlet22bon the compressor side into the inlet23aof the intercooler through the first cooling tube35c.

The air cooled by the intercooler23flows from the outlet23bof the intercooler through the second cooling tube35d, flows into the cylinder13a, and then is combusted. In this manner, the blow-by gas generated in the engine housing20is mixed with the air taken from the outside air, and then is re-combusted.

The working machine1of the present embodiment has the following effects.

The prime mover10includes the fan21to generate a cooling airflow around the engine10, the air-intake tube35to supply the outside air to the engine, the connection tube37to supply, to the air-intake tube35, the blow-by gas generated in the engine10, and the wind shielding, member40to shield the connection tube37from the cooling airflow. The wind shielding member40is arranged around the connection tube37.

According to that configuration, it is possible to avoid that the cooling airflow generated by the fan21directly hits the connection tube37and thereby the connection tube37is cooled. For this reason, even under a cryogenic condition such as a cold area, the blow-by gas can be prevented from being cooled in the connection tube37, and it is possible to suppress freezing of the liquid such as the oil contained in the blow-by gas.

In addition, the connection tube37includes the flow path intersecting portion37a2that intersects with the flow path of the cooling airflow, and the wind shielding member40is arranged at a position opposed to the flow path intersecting portion37a2in the connection tube37. According to that configuration, the wind shielding member40can shut off the cooling airflow flowing to the connection tube37. In this manner, the blow-by gas can be cooled inside the connection tube37, and it is possible to suppress the freezing of the liquid such as the oil and the moisture contained in the blow-by gas.

Further, the fan21is arranged to suck the air from a side of the engine10and to output the air toward a direction separating from the engine10. According to that configuration, the fan21can discharge, to the outside, the air relatively high temperature staying around the engine10. In this manner, the fan21can cool the circumference of the engine10, and cools the intercooler23and the like.

Further, as shown inFIG. 1,FIG. 2,FIG. 8, and the like, the wind shielding member40overlaps with the rotation track RI of the fan21as viewed in the front-rear direction when seen in a direction parallel to a rotation shaft of the fan21. According to that configuration, even when the connection tube37is arranged in the rotation track RI of the fan21where the wind speed of the cooling airflow is relatively strong, the wind shielding member10can prevent the cooling airflow generated by the fan21from directly hitting the connection tube37.

In addition, the connection tube37is arranged above the engine10, and the wind shielding, member40is provided with the first plate portion41arranged on the upstream side of the flow path direction of the cooling airflow in the connection tube37, and a second plate portion42arranged above the connection tube37and extending from the upper portion of the plate portion41toward the downstream side of the cooling airflow in the flow path direction.

According to that configuration, the connection tube37can be appropriately shielded from the cooling airflow.

Further, the opposed portion42C of the connection tube37opposed to the wind shielding member40, includes the curved portion, and the second plate portion42includes the first portion opposed to a portion of the connection tube37, the portion being closer to one end side of the connection tube37than the curved portion, and the second portion42B closer to another portion of the connection tube37, the other portion being closer to the other end side than the curved portion.

According to that configuration, even when the connection tube37is curved, the connection tube37can be covered with the wind shielding member40having a compact configuration. In this manner, the wind shielding member40can be attached to the prime mover10even when the clearance around the prime mover10is narrow.

Further, the prime mover10includes the bracket50to attach the wind shielding member40to the engine10, and the bracket includes the first supporting portion51attached to an upper portion of the engine10, the second supporting portion52supporting the first plate portion41, and the clamp member55clamping the connection tube37.

According to that configuration, the member for attaching the wind shielding member40to the prime mover10and the member for supporting the connection tube37can be provided in a single member. In this manner, the number of members can be reduced, the production process can be reduced, and thus the production cost can be reduced.

Further, the prime mover10includes the filter26to remove the oil included in the blow-by gas. The connection tube37includes one end portion connected to the engine housing20of the engine10, and the other end portion connected to the filter26. And, the wind shielding member40is arranged opposed to a portion of the connection tube37, the portion being closer to the one end portion than a middle portion of the connection tube37between the one end portion and the other end portion.

According to that configuration, it is possible to avoid that the blow-by gas is rapidly cooled by the cooling airflow before the oil is removed from the blow-by gas just having flown into the connection tube37.

That is, the speed of the temperature drop due to the influence of the cooling airflow can be delayed for a time until the blow-by gas reaches the air intake tube35through the connection tube37. That is, the temperature decrease of the blow-by gas can be suppressed in the connection tube37.

In addition, the working machine1is provided with the prime mover10described above. According to that configuration, it is possible to provide the working machine1providing the excellent effect of the wind shielding member40described above.

In the above description, the embodiment of the present invention has been explained. However, all the features of the embodiment disclosed in this application should be considered just as examples, and the embodiment does not restrict the present invention accordingly. A scope of the present invention is shown not in the above-described embodiment but in claims, and is intended to include all modified examples within and equivalent to a scope of the claims.