JP5276975B2 - Engine coolant circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling water circuit for an engine, capable of preventing staying of water vapor generated in a turbo-supercharger, simplifying a structure and making cooling of the engine and warming sufficient. <P>SOLUTION: The cooling water circuit 10 for the engine 1 comprises: a main circuit 11 for circulating cooling water pressure-fed from a water pump 6 to the inside of the engine 1, a thermostat valve 9 and a radiator 30 in the order; and a branch circuit 12 for cooling the turbo-supercharger 3 branched from a position between the water pump 6 in the main circuit 11 and the thermostat valve 9. The branch circuit 12 comprises: a turbo-flowing-in flow passage 22 for communicating the main circuit 11 with the turbo-supercharger 3; and an upper tank returning flow passage 23 for communicating the turbo-supercharger 3 with the upper tank 31 of the radiator 30. A throttle 230 is provided on the turbo-flowing-in flow passage 22. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an engine coolant circuit.

Conventionally, in an engine equipped with a water-cooled turbocharger, it is known to cool the turbocharger with engine cooling water (Patent Document 1).
The cooling water in the cooling water circuit is pressurized by a water pump and flows into the water jacket in the cylinder block, and cools around the liner of each cylinder and then flows into the cylinder head. The cooling water cooled around the injector in the cylinder head flows into the upper tank of the radiator via the thermostat valve and is cooled by heat exchange with the cooling air. The cooled cooling water flows out of the lower tank and returns to the water pump.
A part of the cooling water flowing out from the cylinder head branches and flows into the water jacket of the turbocharger, cools the turbocharger, and returns to the suction side of the water pump.

  By the way, when the engine is stopped, the water pump is also stopped, so that the flow of the cooling water is also stopped. At this time, after the high load operation, the turbocharger is at a high temperature, and in the water jacket of the turbocharger, the accumulated cooling water becomes steam by heat. If the generated water vapor (including bubbles) remains in the turbocharger, it will inhibit heat dissipation in the turbocharger, so that the lubricating oil in the turbocharger will deteriorate, and in some cases the shaft The bearing that supports the rotation will burn out.

  In view of this, in Patent Document 1, a bypass flow path is provided in which such water vapor is quickly released to the upper tank of the radiator. This bypass channel is a channel that connects the inflow side of the turbocharger in the cooling water circuit and the inflow side of the upper tank of the radiator without going through the thermostat valve. It is installed so as to have an upward slope from the supercharger toward the upper tank.

Therefore, since the water vapor generated in the turbocharger moves upward in the bypass flow path and is guided to the upper tank, it can be prevented from remaining in the turbocharger.
Further, since the throttle is provided in the bypass flow path, when the cooling water flows through the cooling circuit, the flow to the bypass flow path side is substantially limited. Accordingly, the cooling water that has flowed into the turbocharger during the warm-up operation bypasses the thermostat and does not flow into the radiator, so that the warm-up operation can be performed satisfactorily.

Japanese Utility Model Publication No. 60-116034

However, in the cooling water circuit described in Patent Document 1, there is a problem that the structure becomes complicated, for example, it is necessary to provide a dedicated bypass channel and to provide a gradient to the bypass channel.
In addition, the cooling water that has cooled the turbocharger always returns to the suction side of the water pump without heat exchange with the radiator, so cooling water that is not sufficiently cooled by the radiator will flow into the engine, resulting in cooling efficiency. There is a problem that is bad.

  An object of the present invention is to provide an engine cooling water circuit that can prevent the stagnation of water vapor generated in a turbocharger, simplify the structure, and improve engine cooling and warm-up operation. .

The engine coolant circuit according to the present invention includes a main circuit for circulating coolant pumped from a water pump in the order of the engine, a thermostat valve, and a radiator, and the water pump and the thermostat valve in the main circuit. A branch circuit for cooling the turbocharger branched from a position between the main circuit and the turbocharger, and the branch circuit communicates the cooling water from the main circuit with the turbocharger. A turbo inflow channel for allowing the turbocharger to flow into the turbocharger; and an upper tank return channel for allowing the coolant to flow into the upper tank from the turbocharger by communicating the turbocharger and the upper tank of the radiator. cooling water which has flowed into the turbocharger to flow out only through the said upper tank return flow path from the turbocharger Wherein the aperture in the turbo inlet channel is provided.

  In the engine coolant circuit according to the present invention, the coolant in the main circuit inside the engine flows into the cylinder head through the cylinder liner of the cylinder block, and then passes through the water manifold in the cylinder block. The turbo inflow passage is branched from the main circuit at an upstream side of the water manifold.

In the engine coolant circuit according to the present invention, the throttle is provided in a joint member for connecting a flow path member of the turbo inflow flow path to the main circuit side.
In the engine coolant circuit according to the present invention, the joint member includes a joint body screwed into a water outlet of the cylinder block, and the joint body includes the water outlet and the axial direction of the joint body. A water inflow hole that communicates is provided, and the water inflow hole includes a large-diameter portion that is located at a predetermined distance from the water outlet and a small-diameter portion that is provided closer to the water outlet than the large-diameter portion. And the small diameter portion is the diaphragm.

  In the engine coolant circuit according to the present invention, the water pump, the thermostat valve, the turbocharger, and the upper tank are arranged in this order from the lowest position.

  In the engine cooling water circuit according to the present invention, the engine is equipped with a dosing fuel injection device for supplying fuel to the exhaust gas purification device, and between the water pump and the thermostat valve in the main circuit. Another branch circuit for cooling the injection device branched from the position of the injection device, and the other branch circuit includes an injection device inflow passage for communicating the main circuit and the injection device, and an upper tank of the injection device and the radiator A communication flow path for communicating with each other, and the injection device inflow flow path is provided with another throttle.

According to the present invention described above, since the throttle is provided in the turbo inflow channel on the cooling water inlet side of the turbocharger, the water vapor generated in the turbocharger immediately after the operation is stopped is not affected by the throttle. It is led to the upper tank through the upper tank return flow path, and excessive temperature rise in the turbocharger due to water vapor is suppressed, and problems such as burning of bearings and the like can be prevented.
Further, since the restriction is not provided in the conventional bypass passage dedicated to water vapor passage, such a bypass passage can be eliminated and the structure can be simplified.

Further, during the warm-up operation of the engine, the cooling water in the main circuit hardly flows to the turbocharger side due to the throttle, and there is no fear of flowing to the radiator side through the turbocharger. Therefore, the cooling water cooled by the radiator does not flow into the engine during the warm-up operation, the engine can be prevented from being excessively cooled, and the warm-up operation can be improved.
Moreover, since the cooling water used for cooling the turbocharger flows into the radiator through the upper tank return flow path and is cooled by the radiator and then returns to the pump, the cooling water is returned to the pump without passing through the radiator. In comparison, the temperature of the cooling water can be lowered, and the cooling efficiency of the engine can be improved.

  In the present invention, by branching the turbo inflow passage upstream from the water manifold from the main circuit, the cooling water pumped from the water pump can be diverted to the turbocharger side in a high water pressure state. The turbocharger can be cooled efficiently.

  In the present invention, by providing the diaphragm integrally as a part of the joint member, parts dedicated to the diaphragm can be omitted, and the reduction of the number of parts can be promoted.

  In the present invention, by disposing the upper tank at the highest position among the constituent members, even if bubbles are generated, the bubbles can be reliably guided to the upper tank, and the air can be stored in the upper tank. Can be merged. For this reason, there is no fear that bubbles may stay in the constituent members on the way and hinder the flow of cooling water.

  In the present invention, when a dosing fuel injection device is mounted on the engine, by providing a throttle also in the injection device inflow channel on the cooling water inlet side of the injection device, the components constituting the injection device are excellent from heat. And the reliability of the injection device can be improved. In addition, with respect to the warm-up performance and cooling efficiency of the engine, the same effects as in the case of the turbocharger can be obtained.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a cooling water circuit 10 according to the present embodiment. The cooling water circuit 10 cools the engine 1 with cooling water, and uses the cooling water to cool the oil cooler 2, the exhaust turbocharger 3, the EGR cooler 4, and exhaust gas purification (not shown). The dosing fuel injection device 5 for the device is cooled.

  The present invention may be a cooling water circuit that cools the exhaust turbocharger 3, and the oil cooler 2, EGR cooler 4, and dosing fuel injection device 5 may be provided as necessary. Furthermore, the dosing fuel injection device 5 and the like are not limited to those mounted on the engine 1, but may be attached to a frame on which the engine 1 is mounted, an exhaust pipe of the engine 1, or the like.

  In the present embodiment, a water pump 6 that pumps cooling water is provided on the lower side of the engine 1, and the water pump 6 is driven by a crankshaft (not shown) in the cylinder block 7. It has become. The oil cooler 2 is attached to the side surface of the cylinder block 7 and is disposed at a position higher than the water pump 6. The EGR cooler 4 is disposed at a height position substantially the same as that of the oil cooler 2 and slightly spaced from the cylinder block 7 to the side. The exhaust turbine supercharger 3 and the dosing fuel injection device 5 are located above the cylinder head 8.

  Specifically, the cooling water circuit 10 includes a main circuit 11 that circulates the cooling water pumped from the water pump 6 as indicated by a thick arrow in the figure, and is branched from the main circuit 11 to each turbocharger. 1 is provided with a first branch circuit (branch circuit) 12 for cooling 3, a second branch circuit 13 for cooling the EGR cooler 4, and a third branch circuit (another branch circuit) 14 for cooling the injection device 5.

  The main circuit 11 includes a first external flow path 15 that allows the water pump 6 and the oil cooler 2 to communicate with each other, and an internal flow path that cools around the cylinder liner in the cylinder block 7, that is, a first water jacket that is not illustrated. An internal flow path 16, a second internal flow path 17 formed in the cylinder head 8, a water manifold (not shown) provided in the cylinder block 7 for collecting cooling water from the cylinder head 8, and an external thermostat valve 9 A third internal flow path 18 that communicates with the thermostat valve 9 and the upper tank 31 of the radiator 30, a third external flow path 20 that communicates the lower tank 32 and the water pump 6 of the radiator 30. And is configured.

  Here, the communication between the water jacket in the cylinder block 7 and the cylinder head 8 and the communication between the inside of the cylinder head 8 and the water manifold are performed by a bore hole provided between the cylinder block 7 and the cylinder head 8. . The first internal flow path 16, the second internal flow path 17, and the third internal flow path 18 communicate with each other in the engine 1 by these drill holes. Further, the second internal channel 17 and the second external channel 19 are communicated with each other by a discharge channel 21 for removing bubbles. The attachment position of the thermostat valve 9 is preferably between the attachment position of the water pump 6 and the connection position of the discharge passage 21 to the second external passage 19, more preferably at the outlet position of the third internal passage 18. is there.

The first branch circuit 12 for cooling the turbocharger 3 includes a turbo inflow passage 22 for communicating a water jacket in the cylinder block 7 with a water jacket provided in a housing of the turbocharger 3, and a turbocharger. An upper tank return flow path 23 is provided for communicating the water jacket of the feeder 3 and the upper tank 31 of the radiator 30.
As the turbocharger 3 in the present embodiment, a variable turbocharger that can adjust the nozzle opening on the exhaust turbine side is adopted.

  The second branch circuit 13 for cooling the EGR cooler 4 is connected to the cooler inflow channel 24 branched from the first external channel 15 and connected to the water inlet of the EGR cooler 4, and the water outlet of the EGR cooler 4. A pump return passage 25 joined to the third external passage 20 on the suction side (upstream side) of the water pump 6 is provided.

  The third branch circuit 14 for cooling the injection device 5 is connected to the cylinder block 7 and communicates an internal water jacket with a water jacket provided in the housing of the injection device 5, and an injection device A communication channel 27 is provided for communicating the water jacket of the apparatus 5 with the upper tank return channel 23.

The dosing fuel from the injection device 5 is configured so that the exhaust gas purification device includes a suit filter that captures particulate matter in the exhaust gas and an oxidation catalyst disposed upstream thereof. The exhaust gas is supplied to the oxidation catalyst while being injected into the exhaust gas, and is oxidized and heated to raise the exhaust gas temperature to the regeneration temperature of the suit filter.
On the other hand, the particulate matter captured by the suit filter is burned and removed by the heat of the exhaust gas, which has reached a high temperature up to the regeneration temperature, rendered harmless and discharged to the outside together with the exhaust gas. This regenerates the suit filter and prevents the suit filter from being clogged by particulate matter.

  In addition to the above, the thermostat valve 9 and the water pump 6 communicate with each other through a warm-up flow path 28 (dotted line arrow in the figure). In a low state in which the cooling water does not reach the predetermined temperature, the cooling water is returned to the water pump 6 without passing through the radiator 30 by the thermostat valve 9 so that the warm-up operation of the engine 1 can be performed satisfactorily. The thermostat valve 9 is entirely covered with a housing 9A.

  Further, in FIG. 1, the height positional relationship between the turbocharger 3 and the injection device 5 with respect to the thermostat valve 9 in the engine 1 is schematically illustrated. Is disposed at a higher position than the thermostat valve 9. Furthermore, the discharge passage 21 for removing bubbles, the second external passage 19 that is the junction of the discharge passage 21, the upper tank return passage 23 from the turbocharger 3, and the communication passage 27 The air bubbles flowing through the upper tank 31 can be reliably reached without staying in the middle. For this reason, for example, the discharge flow path 21 is preferably arranged at a position higher than the upper surface of the cylinder head 8, and the upper tank 31 is arranged at the highest position among the members shown in FIG. .

  Hereinafter, in the first branch circuit 12 for cooling the turbocharger 3 in particular, the turbo inflow passage 22 will be described in detail. As shown in FIG. 2, the turbo inflow channel 22 includes a channel member 221 made of a heat-resistant resin hose or a metal tube, and a joint for connecting the base end side of the channel member 221 to the cylinder block 7. The member 222 is configured to include a joint member (not shown) for connecting the distal end side of the flow path member 221 to the housing of the turbocharger 3.

  In FIG. 2, the joint member 222 includes a joint body 223 screwed into the water outlet 71 of the cylinder block 7 and a rotating member 224 that is rotatably inserted into the joint body 223 and functions as a swivel joint. .

That is, the joint main body 223 is provided with a water inflow hole 225 along the axial direction and a plurality of communication holes 226 that penetrate in the radial direction and communicate with the water inflow hole 225. The rotary member 224 includes a transmural insertion hole 227 along the rotation axis, orthogonal to the rotation axis and the water outlet hole 228 is provided, the joint main body 223 is inserted through the transmural insertion hole 227 was inserted through In this state, the communication hole 226 and the water outflow hole 228 communicate with each other.

  A plurality of seal grooves 229 are provided on the outer periphery of the joint body 223, and seal rings (not shown) are disposed in the seal grooves 229, and the joint body 223 and the rotating member 224 are disposed by these seal rings. The space is sealed.

  Accordingly, the cooling water from the water jacket in the cylinder block 7 enters the water inlet hole 225 of the joint body 223 from the water outlet 71 and is guided to the water outlet hole 228 of the rotating member 224 through the communication hole 226. It flows out to the flow path member 221 attached to the opening end side of the.

  By the way, the water inflow hole 225 of the joint body 223 has a large inner diameter on the far side away from the water outlet 71 and a small inner diameter on the opening end side close to the water outlet 71. That is, a throttle 230 having a smaller diameter than the back side is provided on the opening end side of the water inflow hole 225. The throttle 230 has a function of suppressing the flow of cooling water of a required flow rate or more from the main circuit 11 (specifically, a water jacket) branching to the turbocharger 3 side.

  As a result, even during the warm-up operation in which the coolant flows from the thermostat valve 9 through the warm-up flow path 28, the coolant does not flow too much through the first branch circuit 12 to the radiator 30 side. It is possible to prevent lowering than necessary and to perform warm-up operation well.

Such a throttle can be provided, for example, in a joint member for connecting the housing of the turbocharger 3 and the flow path member of the upper tank return flow path 23 (FIG. 1). Since it is located downstream of the supercharger 3, when the operation is stopped, water vapor generated by heat soak back cannot pass through the throttle and is not led to the upper tank 31. As a result, the temperature of the bearing or the like exceeds the temperature limit, and there is a possibility of seizing.

  On the other hand, in the present embodiment, since the throttle 230 is provided in the turbo inflow passage 22 on the inlet side (downstream side) of the turbocharger 3, the steam generated in the turbocharger 3 is throttled 230. Without being influenced by the above, it is possible to reliably escape to the upper tank 31 through the upper tank return flow path 23, and it is possible to prevent the turbocharger 3 from becoming excessively hot and prevent the bearings and the like from being seized.

FIG. 3 shows measurement of the temperature A of the bearing over time when the throttle 230 is provided on the turbo inflow channel 22 side (this embodiment), and the measurement when the throttle 230 is provided on the upper tank return channel 23 side. Temperature B is indicated. The temperature measurement was performed until the predetermined time had elapsed after the engine 1 was suddenly stopped from the state of high load operation. The temperature measurement B results in exceeding the temperature limit, and there is a concern about bearing seizure. On the other hand, the temperature measurement A does not exceed the temperature limit, and the effectiveness in this embodiment is recognized.
When the throttle 230 is not provided, a result that is even lower than the temperature measurement A is obtained, but the flow rate of the cooling water that flows to the turbocharger 3 side increases, and the flow rate that flows to the radiator 30 side increases. Warm-up performance is reduced.

  Further, in the present embodiment that employs a variable turbocharger in particular, a mechanism for adjusting the nozzle opening is provided, but the temperature of the turbocharger 3 is maintained sufficiently below the temperature limit. Moreover, the thermal influence with respect to the precise | minute member which comprises such a mechanism can also be suppressed, and the reliability of the turbocharger 3 can be improved.

  In addition, in the present embodiment, the steam generated in the turbocharger 3 is not provided with a dedicated bypass passage for passing water vapor, or the throttle 230 is provided in the bypass passage. Since it is provided in the first branch circuit 12 inevitably used for cooling the supercharger 3, the piping structure can be simplified. In particular, the diaphragm 230 is formed on the joint member 222, thereby reducing the number of parts and saving space.

  Further, although detailed explanation is omitted, in the third branch circuit 14 for cooling the injection device 5, the throttle (another throttle) 231 provided in the injection device inflow channel 26 is the same as the throttle 230. Is provided. The injection device 5 is also considered as a heat source in the cooling water circuit 10, and there is a possibility that water vapor is generated as in the turbocharger 3. Therefore, by providing the throttle 231 in the injection device inflow channel 26, the same effect as when the throttle 230 is provided in the turbo inflow channel 22 can be obtained.

  In the cooling water circuit 10 described above, during the warm-up operation immediately after the start of the engine 1, the cooling water in the main circuit 11 returns from the thermostat valve 9 to the suction side of the water pump 6 through the warm-up flow path 28, Prevents cooling water temperature from dropping too much during warm-up operation. At this time, in the first branch circuit 12 and the third branch circuit 14, since the throttles 230 and 231 are provided, the flow rate of the cooling water flowing to the radiator 30 side is suppressed as described above, and the warm-up operation is hindered. You don't have to.

  On the other hand, when the temperature of the cooling water is equal to or higher than the predetermined temperature, the thermostat valve 9 is switched, and the cooling water in the main circuit 11 flows from the thermostat valve 9 through the second external flow path 19 into the radiator 30 to be cooled. The process returns to the water pump 6. Therefore, the engine 1, the oil cooler 2, the exhaust turbocharger 3, the EGR cooler 4, and the injection device 5 are efficiently cooled by the cooling water after heat exchange.

The best configuration, method, and the like for carrying out the present invention have been disclosed above, but the present invention is not limited to this. That is, the invention has been illustrated and described with particular reference to certain specific embodiments, but without departing from the spirit and scope of the invention, Various modifications can be made by those skilled in the art in terms of quantity and other detailed configurations.
Therefore, the description limited to the shape, quantity and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  For example, in the above-described embodiment, the case where the turbocharger 3 is used as a heat source has been described as an example. However, the heat source may be the dosing fuel injection device 5 or the EGR cooler 4 depending on the case. Good. Further, in the third branch circuit 14 for cooling the injection device 5, the communication flow path 27 joins the upper tank return flow path 23, and communicates with the upper tank 31 via the upper tank return flow path 23. However, the communication channel 27 may be joined directly to the upper tank 31.

  The above embodiment is an example in which a variable turbocharger is employed as the turbocharger 3, but the present invention can be applied even when the nozzle opening is not variable as the turbocharger. However, by applying the present invention to the variable turbocharger, the components of the nozzle opening adjustment mechanism can be reliably protected from heat in addition to the main shaft bearing, which is more effective.

  In the above-described embodiment, the example in which the joint member 222 is integrally provided as the throttle of the present invention has been described. However, the throttle having a smaller diameter portion than the inner diameter of the channel member 221 in the channel member 221 of the turbo inflow channel 22. Is formed in the middle or by another member, or by adopting a flow path member 221 having an inner diameter smaller than the inner diameter of the flow path member forming the upper tank return flow path 23. The entire member 221 itself may function as a diaphragm, and any member or shape can be applied in the implementation.

  However, by providing the joint member 222 as in the above-described embodiment, the pipe diameters of the flow path member 221 in the turbo inflow flow path 22 and the flow path member in the upper tank return flow path 23 are the same. Therefore, it is possible to prevent an increase in the number of types of pipes and to prevent erroneous assembly of the pipes, which is preferable. Further, by providing the throttle on the joint member 222, the influence of the vibration of the turbocharger 3 disposed on the upper portion of the engine 1 can be reduced as compared with the case where the throttle is formed by the flow path member 221 itself having a smaller inner diameter. It can be made difficult to receive, can be prevented from being damaged by vibration, etc. and can improve durability.

  In the above-described embodiment, each of the flow paths 15 to 20 is defined as an internal flow path that is formed inside the cylinder block 7 and the cylinder head 8, and an external flow path that is formed of an external metal pipe or hose. However, it is arbitrary whether each flow path 15-20 is formed inside or outside them, or what member is used, and may be appropriately determined in the implementation.

In the embodiment, the first and second branch circuits 12 and 14 are branched from the first internal flow path 16 formed by a water jacket or the like, but the first external flow path 15 or the third internal flow path 18 is used. You may branch from. However, since the cooling water can be efficiently supplied with a larger water pressure when the water pump 6 is branched from the flow path, the first external flow path 15 and the first internal flow are separated from the third internal flow path 18. It is better to branch off from the road 16.

  INDUSTRIAL APPLICABILITY The present invention can be used for construction machines, transportation vehicles, civil engineering vehicles, power generation facilities and the like equipped with an engine with a turbocharger.

The circuit diagram which shows the cooling water circuit which concerns on one Embodiment of this invention. Sectional drawing which shows the principal part of the said embodiment. The figure which shows the effectiveness of the said embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... Turbocharger, 5 ... Dosing fuel injection device, 6 ... Water pump, 7 ... Cylinder block, 9 ... Thermostat valve, 10 ... Cooling water circuit, 11 ... Main circuit, 12 ... First branch circuit DESCRIPTION OF SYMBOLS 14 ... 3rd branch circuit, 22 ... Turbo inflow flow path, 23 ... Upper tank return flow path, 26 ... Injection apparatus inflow flow path, 27 ... Communication flow path, 30 ... Radiator, 31 ... Upper tank, 222 ... Joint member , 230, 231.

Claims (6)

In the engine coolant circuit,
A main circuit for circulating cooling water pumped from a water pump in the order of the engine, a thermostat valve, and a radiator;
A turbocharger cooling branch circuit branched from a position between the water pump and the thermostat valve in the main circuit,
This branch circuit is
A turbo inflow passage for communicating the main circuit and the turbocharger to flow the cooling water from the main circuit into the turbocharger;
An upper tank return channel for communicating the turbocharger and the upper tank of the radiator to flow the cooling water from the turbocharger into the upper tank;
The cooling water flowing into the turbocharger is discharged from the turbocharger only through the upper tank return flow path,
An engine cooling water circuit, wherein the turbo inflow passage is provided with a throttle. The engine coolant circuit according to claim 1,
The cooling water of the main circuit inside the engine passes through the cylinder liner of the cylinder block and flows into the cylinder head, and then passes through the water manifold of the cylinder block to reach the thermostat valve.
The turbo inflow passage is branched from the main circuit at an upstream side of the water manifold. The engine coolant circuit according to claim 1 or 2,
The throttle is provided in a joint member for connecting a flow path member of the turbo inflow flow path to the main circuit side. The engine coolant circuit according to claim 3,
  The joint member includes a joint body screwed into a water outlet of the cylinder block,
  The joint body is provided with a water inflow hole communicating with the water outlet along the axial direction of the joint body,
  The water inflow hole includes a large diameter portion located at a position away from the water outlet by a predetermined distance, and a small diameter portion provided on the water outlet side than the large diameter portion,
  The small diameter portion is the diaphragm
  An engine cooling water circuit characterized by that. The engine coolant circuit according to any one of claims 1 to 4 ,
The engine coolant circuit, wherein the water pump, the thermostat valve, the turbocharger, and the upper tank are arranged in this order from the lowest arrangement position. The engine coolant circuit according to any one of claims 1 to 5 ,
The engine is equipped with a dosing fuel injection device that supplies fuel to the exhaust gas purification device,
Another branch circuit for cooling the injector branched from a position between the water pump and the thermostat valve in the main circuit,
This other branch circuit is
An injection device inflow passage for communicating the main circuit and the injection device;
A communication flow path for communicating the injection device and the upper tank of the radiator,
An engine cooling water circuit, wherein the injection device inflow channel is provided with another throttle.

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