JP2011012660A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent freezing of a liquid reducing agent while achieving simplified structure and reduced equipment costs and without wasting energy.SOLUTION: In a construction machine mounted with a heat exchanger unit 13 in an engine room 7 and with a liquid reducing agent tank 11 storing a liquid reducing agent, the liquid reducing agent tank 11 is disposed in the heat exchanger unit 13, so that the liquid reducing agent tank 11 can be kept warm.

Description

  The present invention relates to a construction machine, and more particularly, to a construction machine equipped with a liquid reducing agent tank storing a liquid reducing agent.

  In recent years, construction equipment such as hydraulic excavators equipped with diesel engines has been equipped with exhaust gas treatment equipment in the exhaust system of diesel engines to meet higher-level exhaust gas regulations. Is released into the atmosphere through the NOx reduction catalyst provided in

  Conventionally, as this kind of exhaust gas treatment apparatus, a urea selective reduction type NOx treatment apparatus using a urea aqueous solution (liquid reducing agent) is often adopted, and the urea aqueous solution is stored in a liquid reducing agent tank. The liquid reducing agent tank is connected to the exhaust pipe by a liquid reducing agent supply pipe, and the urea aqueous solution in the liquid reducing agent tank can be supplied to the downstream side of the exhaust pipe by the liquid reducing agent supply pump. (For example, refer to Patent Document 1).

JP 2003-20936 A

  The aqueous urea solution is easily frozen at a low temperature below freezing point, and when it is frozen, the aqueous urea solution cannot be used as a liquid reducing agent. Therefore, various techniques for preventing freezing of the urea aqueous solution have been developed. For example, by installing a heater (heating means) in the liquid reducing agent tank and attaching a temperature sensor, and outputting a command signal from the computer to the heater (temperature control means) based on the detection signal from the temperature sensor, the liquid A technology for heating the inside of the reducing agent tank has been developed.

  However, when the heating means and the temperature control means are provided as described above, the structure is complicated and the equipment cost increases. In particular, during cold weather, it is necessary to constantly heat the liquid reducing agent tank in order to prevent freezing of the aqueous urea solution in the liquid reducing agent tank, which increases the consumption of electric energy for heating. It was.

  Therefore, there is a technical problem to be solved in order to simplify the structure, reduce the equipment cost, and prevent freezing of the liquid reducing agent without wasting energy. The purpose is to solve the problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a construction machine equipped with a liquid reducing agent tank storing a liquid reducing agent, wherein the liquid reducing agent tank is mounted on the construction machine. Is provided in a heat exchanger unit disposed in front of the engine, thereby providing a construction machine characterized in that the liquid reducing agent tank can be kept warm.

  According to this configuration, the heat exchanger unit is warmed by heat radiation from the engine and is held at a predetermined temperature or higher, so that the liquid reducing agent tank installed in the heat exchanger unit is also held at a predetermined temperature or higher. Therefore, even during cold weather, the liquid reducing agent stored in the liquid reducing agent tank is stably maintained at a temperature that does not freeze.

  According to the first aspect of the present invention, since the liquid reductant tank installed in the heat exchanger unit has improved heat retention and can be maintained at a predetermined temperature or higher, the liquid reductant in the liquid reductant tank can be frozen even in cold weather. Can be prevented.

  In this case, unlike the conventional example, no special equipment such as a special heater or temperature control means is required, so that the structure is simplified, the equipment cost is reduced, and the waste of energy can be eliminated.

The side view of the hydraulic excavator (construction machine) which shows one Example of this invention. The top view which shows the upper turning body of the hydraulic shovel which concerns on one Example. The perspective view explaining the installation location of the tank for liquid reducing agents which concerns on one Example.

  In order to achieve the object of simplifying the structure, reducing the equipment cost, and preventing the freezing of the liquid reducing agent without wasting energy, the present invention provides a liquid reducing agent tank that stores the liquid reducing agent. In the installed construction machine, the liquid reducing agent tank is installed in a heat exchanger unit disposed in front of the engine, and the liquid reducing agent tank can be kept warm.

  A preferred embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a hydraulic excavator as an example of a construction machine. As shown in the figure, an upper swing body 2 is mounted on the lower traveling body 1 so as to be capable of swinging, and a cab 3 is provided on one front side of the upper swing body 2. In addition, the boom 4 is pivotally attached to the front center portion of the upper swing body 2 so that the boom 4 can be raised and lowered, and an arm 5 is connected to the distal end portion of the boom 4 so as to be rotatable up and down. A bucket 6 is attached so as to be rotatable up and down.

  As shown in FIG. 2, an engine room 7 is provided at the rear of the upper swing body 2, and a diesel engine 8 is installed in the engine room 7. An exhaust pipe 9 is connected to the diesel engine 8, and an exhaust gas treatment device 10 is installed on the downstream side of the exhaust pipe 9 in order to comply with higher-order exhaust gas regulations. As the exhaust gas treatment apparatus 10 according to the present embodiment, a urea selective reduction type NOx treatment apparatus using a urea aqueous solution (liquid reducing agent) is adopted.

  A cooling fan 12 is disposed in front of the diesel engine 8 (front side in FIG. 2), and a heat exchanger unit 13 is installed in front of the cooling fan 12.

  As shown in FIG. 3, an oil cooler 14 is installed in the center of the heat exchanger unit 13. Further, a radiator 15 is installed on the right side of the oil cooler 14, and a metallic liquid reducing agent tank 11 is installed on the left side of the oil cooler 14. In the liquid reducing agent tank 11, an aqueous urea solution used in the exhaust gas treatment device 10 is stored. The liquid reducing agent tank 11 is connected to the exhaust gas treatment device 10 via a liquid reducing agent supply pipe (not shown).

  As described above, according to the present invention, since the liquid reducing agent tank 11 is disposed in the heat exchanger unit 13 arranged in front of the diesel engine 8, the heat retaining property of the liquid reducing agent tank 11 is improved.

  That is, during operation of the diesel engine 8, the temperature in the engine room 7 is warmed to a predetermined value or higher due to heat released from the diesel engine 8, so that the temperature in the heat exchanger unit 13 is also maintained to be a predetermined value or higher. . Therefore, the liquid reducing agent tank 11 is also always kept warm above a predetermined temperature.

  Thus, for example, even in a cold region where the temperature is below freezing, the temperature of the liquid reducing agent tank 11 can be maintained at a predetermined temperature or higher, so that the urea aqueous solution in the liquid reducing agent tank 11 can be frozen in a low temperature environment. Can be prevented.

  In this case, since the liquid reducing agent tank 11 can be maintained at a predetermined temperature or higher by being installed in the existing heat exchanger unit 13, no additional equipment such as a heating means such as a heater or temperature control is required. Therefore, the structure is simplified as compared with the conventional example, and the equipment cost is almost unnecessary, and in addition, the waste of electric energy for heating the liquid reducing agent tank 11 is eliminated.

  In addition, since the liquid reducing agent tank 11 is installed in the heat exchanger unit 13, the degree of freedom in layout is improved.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

  The present invention can be applied to any construction machine equipped with a liquid reducing agent tank in which a liquid reducing agent other than an aqueous urea solution is stored in the liquid reducing agent tank.

2 Upper revolving body 7 Engine room 8 Diesel engine 9 Exhaust pipe 10 Exhaust gas treatment device 11 Liquid reductant tank 13 Heat exchanger unit 14 Oil cooler 15 Radiator

Claims (1)

In a construction machine equipped with a liquid reducing agent tank in which a liquid reducing agent is stored, the liquid reducing agent tank is installed in a heat exchanger unit disposed in front of the engine, thereby the liquid reducing agent tank. Construction machine characterized by being able to keep warm.

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