Engine device

1. An engine device comprising:

a urea injection nozzle which injects urea water into exhaust gas of an engine;

a urea mixing pipe configured to mix the urea water from the urea injection nozzle into exhaust gas of the engine;

an exhaust gas purification case which removes nitrogen oxide in the exhaust gas of the engine; and

the engine device being structured such that an exhaust gas inlet pipe of the exhaust gas purification case is connected to an outlet of the urea mixing pipe via a flange body,

wherein exhaust gas outlet side end portions of an outer pipe and an inner pipe of the urea mixing pipe having a double-pipe structure are connected to exhaust gas inlet side end portions of an outer pipe and an inner pipe of the exhaust gas inlet pipe having a double-pipe structure, a fitting small-diameter portion is formed in an end portion of the inner pipe of the urea mixing pipe, and the fitting small-diameter portion is inward insert to an inner portion of the inner pipe of the exhaust gas inlet pipe.

2. The engine device according to claim 1 , wherein the outer pipe of the exhaust gas inlet pipe and the outer pipe of the urea mixing pipe are formed by a pipe having the same diameter, and the inner pipe of the exhaust gas inlet pipe and the inner pipe of the urea mixing pipe are formed by a pipe having the same diameter.

3. The engine device according to claim 1 , wherein a pipe thickness of the inner pipe of the urea mixing pipe is formed thinner than a pipe thickness of the outer pipe of the urea mixing pipe.

4. An engine device comprising:

a urea injection nozzle which injects urea water into exhaust gas of an engine;

a urea mixing pipe configured to mix the urea water from the urea injection nozzle into exhaust gas of the engine;

an exhaust gas purification case which removes nitrogen oxide in the exhaust gas of the engine; and

the engine device being structured such that an exhaust gas inlet pipe of the exhaust gas purification case is connected to an outlet of the urea mixing pipe via a flange body,

wherein exhaust gas outlet side end portions of an outer pipe and an inner pipe of the urea mixing pipe having a double-pipe structure are connected to exhaust gas inlet side end portions of an outer pipe and an inner pipe of the exhaust gas inlet pipe having a double-pipe structure, an exhaust gas inlet side end portion of the inner pipe of the exhaust gas inlet pipe is fitted to an exhaust gas outlet side end portion of the inner pipe of the urea mixing pipe, and an exhaust gas outlet side end portion of the inner pipe of the urea mixing pipe is supported to the outer pipe of the urea mixing pipe.

5. The engine device according to claim 4 , wherein the exhaust gas outlet side end portion of the urea mixing pipe is provided with a support body which connects an outer peripheral surface of the inner pipe to an inner peripheral surface of the outer pipe of the urea mixing pipe.

6. The engine device according to claim 4 , wherein an inner diameter of the inner pipe of the exhaust gas inlet pipe is formed larger than an outer diameter of the inner pipe of the urea mixing pipe, the outer pipe and the inner pipe of the exhaust gas inlet pipe are firmly fixed to an inlet side flange body serving as the flange body, the outer pipe of the urea mixing pipe is firmly fixed to an outlet side flange body serving as the flange body, and the inlet side flange body and the outlet side flange body are fastened.

7. An engine device comprising:

a urea injection nozzle which injects urea water into exhaust gas of an engine;

a urea mixing pipe configured to mix the urea water from the urea injection nozzle into exhaust gas of the engine;

an exhaust gas purification case which removes nitrogen oxide in the exhaust gas of the engine; and

the engine device being structured such that an exhaust gas inlet pipe of the exhaust gas purification case is connected to an outlet of the urea mixing pipe via a flange body,

wherein exhaust gas outlet side end portions of an outer pipe and an inner pipe of the urea mixing pipe having a double-pipe structure are connected to exhaust gas inlet side end portions of an outer pipe and an inner pipe of the exhaust gas inlet pipe having a double-pipe structure, a ring-like pinching piece portion is formed in the exhaust gas inlet side end portion of the inner pipe of the exhaust gas inlet pipe by folding the exhaust gas inlet side end portion of the inner pipe of the exhaust gas inlet pipe toward an outer side, and a ring-like pinching piece portion is formed in the exhaust gas outlet side end portion of the inner pipe of the urea mixing pipe by folding the exhaust gas outlet side end portion of the inner pipe of the urea mixing pipe toward an outer side.

8. The engine device according to claim 7 , wherein ring-like pinching piece portions are formed in the exhaust gas inlet side end portions of the outer pipe and the inner pipe of the exhaust gas inlet pipe by folding the exhaust gas inlet side end portions of the outer pipe and the inner pipe of the exhaust gas inlet pipe toward outer sides, and ring-like pinching piece portions are formed in the exhaust gas outlet side end portions of the outer pipe and the inner pipe of the urea mixing pipe by folding the exhaust gas outlet side end portions of the outer pipe and the inner pipe of the urea mixing pipe.

9. The engine device according to claim 7 , wherein the exhaust gas inlet side end portion of the outer pipe of the exhaust gas inlet pipe or the exhaust gas outlet side end portion of the outer pipe of the urea mixing pipe is brought into contact with an outer peripheral surface of the inner pipe by being folded toward an inner side.