JP2009257122A - Exhaust emission control device of hydraulic working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently prevent freezing of a reducing agent, in an exhaust emission control device of a hydraulic working machine. <P>SOLUTION: This exhaust emission control device 1 of the hydraulic working machine has a hydraulic fluid tank 4 for storing a hydraulic fluid for operating the hydraulic working machine and a reducing agent tank 13 storing the reducing agent for purifying exhaust gas of an engine 2, and has a reducing catalyst 7 built in a muffler 6 of the engine 2, an injection nozzle 11 injecting the reducing agent toward the exhaust flow passage upstream side of the reducing catalyst 7, a reducing agent supply passage 14 supplying the reducing agent to the injection nozzle 11 from the reducing agent tank 13, and a hydraulic fluid heater 31 interposed in the reducing agent supply passage 14 and warming the reducing agent by using the hydraulic fluid returning to the hydraulic fluid tank 4. The reducing agent tank 13 is built in the hydraulic fluid tank 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust purification device mounted on a hydraulic work machine.

Conventionally, a technology for preventing freezing of a reducing agent used for exhaust purification of an engine has been developed. For example, in Patent Document 1, a part of a passage of cooling water heated by an engine is led to a reducing agent tank and reduced. A technique for preventing freezing of the reducing agent stored in the agent tank is disclosed.
JP 2006-125331 A

However, in the technique disclosed in Patent Document 1, when a vehicle is left in a cold region for a long time, there is a problem that the cooling water is cooled and the reducing agent in the reducing agent tank is frozen. Further, in a hydraulic working machine such as a hydraulic excavator, there is a problem that it is difficult to control the temperature of the reducing agent because the temperature change of the cooling water is significant due to the load of the engine.
The present invention has been devised in view of such a problem, and an object of the present invention is to provide an exhaust purification device for a hydraulic working machine that can prevent the reducing agent from freezing.

  In order to achieve the above object, an exhaust purification device for a hydraulic work machine according to a first aspect of the present invention comprises a hydraulic oil tank for storing hydraulic oil for operating the hydraulic work machine, an exhaust purification device for the engine. An exhaust purification device for a hydraulic work machine having a reducing agent tank for storing a reducing agent for the reduction catalyst built in the muffler of the engine, and toward the upstream side of the exhaust passage of the reduction catalyst An injection nozzle that injects the reducing agent, a reducing agent supply passage that supplies the reducing agent from the reducing agent tank to the injection nozzle, and the hydraulic oil that is interposed in the reducing agent supply passage and returns to the hydraulic oil tank And a hydraulic oil heater that warms the reducing agent, and the reducing agent tank is built in the hydraulic oil tank.

The exhaust gas purification apparatus for a hydraulic work machine according to a second aspect of the present invention is the exhaust gas purification apparatus for a hydraulic work machine according to the first aspect, wherein the reducing agent tank is surrounded by a heat insulating material. .
The exhaust gas purification apparatus for a hydraulic work machine according to a third aspect of the present invention is the exhaust gas purification apparatus for a hydraulic work machine according to the first or second aspect, wherein the temperature of the reducing agent in the reducing agent supply passage is detected. Temperature detection means, and control means for controlling the flow rate of the hydraulic oil supplied to the hydraulic oil heater, the control means based on the temperature of the reducing agent detected by the temperature detection means, The flow rate of the hydraulic oil supplied to the hydraulic oil heater is controlled.

  The exhaust gas purification apparatus for a hydraulic work machine according to claim 4 of the present invention is the exhaust gas purification apparatus for a hydraulic work machine according to claim 3, further comprising an electric heater interposed in the reducing agent supply passage, The control means operates the electric heater based on the temperature of the reducing agent detected by the temperature detection means.

  According to the exhaust gas purification apparatus for a hydraulic work machine of the first aspect of the present invention, since the reducing agent tank is built in the hydraulic oil tank, the reducing agent tank is hardly affected by the outside air temperature. Even if it exists, freezing of a reducing agent can be prevented favorably. Moreover, since the hydraulic oil heater can warm the reducing agent, even when the temperature of the reducing agent is low, the temperature can be quickly increased, and the exhaust purification efficiency can be improved.

  According to the exhaust gas purification apparatus for a hydraulic working machine of the second aspect of the present invention, since the reducing agent tank is surrounded by the heat insulating material, the reducing agent tank becomes less susceptible to the influence of the outside air temperature. Freezing can be prevented better. In addition, the influence of the temperature (oil temperature) of the hydraulic oil in the hydraulic oil tank can be reduced, and there is a risk that the reducing agent will be excessively warmed especially when the oil temperature in the hydraulic oil tank becomes too high. It is effective.

According to the exhaust gas purification apparatus for a hydraulic work machine of the present invention as set forth in claim 3, the control means controls the flow rate of the hydraulic oil supplied to the hydraulic oil heater based on the detected temperature of the reducing agent. The temperature can be controlled stably and satisfactorily.
According to the exhaust gas purification apparatus for a hydraulic work machine of the fourth aspect of the present invention, since the electric heater is further provided, the temperature of the reducing agent can be increased more quickly, and the exhaust gas purification efficiency can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[One Embodiment]
An embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram of an exhaust emission control device for a hydraulic work machine according to an embodiment of the present invention.

<Configuration>
As shown in FIG. 1, an exhaust purification device 1 includes an engine 2 as a drive source of a hydraulic excavator (hydraulic work machine), hydraulic pumps 3A and 3B driven by the engine 2 and discharging hydraulic oil, and hydraulic oil. The hydraulic oil tank 4 to be stored, the exhaust pipe 5 of the engine 2, a muffler 6 interposed in the exhaust pipe 5, and a reduction catalyst 7 built in the muffler 6 are configured.

  Further, the exhaust purification device 1 includes an injection nozzle 11 that is penetrated into the muffler 6 and injects the reducing agent toward the upstream side of the exhaust passage of the reduction catalyst 7, and an electromagnetic reducing agent that adjusts the injection amount of the reducing agent. An injection amount control valve (hereinafter referred to as a reducing agent valve) 12, a reducing agent tank 13 that stores the reducing agent, and a reducing agent supply passage 14 that supplies the reducing agent stored in the reducing agent tank 13 to the injection nozzle 11. It is comprised.

Here, the reducing agent is, for example, a urea aqueous solution, and the reduction catalyst 7 is, for example, a urea addition type NO _x selective reduction catalyst (so-called SCR catalyst), which utilizes NH ₃ (ammonia) obtained by hydrolysis of urea. the Te NO _x in which changing into harmless N ₂ (nitrogen).
The reducing agent tank 13 is surrounded by a heat insulating material 15 and is built in the hydraulic oil tank 4. The heat insulating material 15 is hatched so as to be easily identified in FIG.

Further, the exhaust purification device 1 stores air, an air compressor 21 that pressurizes the reducing agent in the reducing agent tank 13 with compressed air and pushes it to the reducing agent supply passage 14, an electric motor 22 that drives the air compressor 21, and air. An air tank 23 and an air dryer 24 that removes moisture from the compressed air are provided.
The exhaust emission control device 1 includes a hydraulic oil heater 31 that warms the reducing agent using hydraulic oil, and an electromagnetic hydraulic oil flow control valve that controls the flow rate of the hydraulic oil flowing through the hydraulic oil heater 31 (hereinafter referred to as hydraulic oil). 32) and an electric heater 33 that warms the reducing agent by using electricity.

The hydraulic oil heater 31 is discharged from the hydraulic pumps 3 </ b> A and 3 </ b> B and supplied to various hydraulic actuators (for example, a boom hydraulic cylinder, a turning hydraulic motor, and a traveling hydraulic motor) and is supplied to the hydraulic oil tank 4. It is a heater that warms the reducing agent using warmed hydraulic oil before returning. That is, the hydraulic oil heater 31 is a heater as a heat exchanger that uses the hydraulic oil as a heat source and moves the heat of the hydraulic oil to the reducing agent to warm the reducing agent.
The electric heater 33 is a well-known heater that warms the reducing agent using heat obtained by electric energy. In other words, the electric heater 33 is a heater as an electric heater that uses electricity as a heat source and warms the reducing agent with the heat obtained from the electric energy. For example, the electric heater 33 flows electricity through a conductor (heating element) to heat the conductor. The reducing agent is heated by the heat generated by the conductor.

The hydraulic oil heater 31 and the electric heater 33 are interposed on the reducing agent supply passage 14 and can warm the reducing agent flowing through the reducing agent supply passage 14.
Further, the exhaust purification device 1 includes a temperature sensor 41 that detects the temperature of the reducing agent and a controller (control means) 42. The temperature sensor 41 detects the temperature T of the reducing agent on the downstream side of the electric heater 33 in the reducing agent supply passage 14.

  The controller 42 has a temperature sensor 41 connected to the input side, and a hydraulic oil valve 32, an electric heater 33, and a reducing agent valve 12 connected to the output side. Based on the temperature T of the reducing agent input from the temperature sensor 41, the hydraulic oil valve 32 is controlled to control the flow rate of the hydraulic oil, the electric heater 33 is operated, or the reducing agent valve. 12 is controlled.

Specifically, the controller 42 determines that the reducing agent is cold if the temperature T of the reducing agent is equal to or lower than a predetermined temperature, and sends an electric signal to the hydraulic oil valve 32 to the hydraulic oil heater 31. The flow rate of the supplied hydraulic oil is maximized, and an electric signal is sent to the electric heater 33 to operate the electric heater 33. On the other hand, if the temperature T of the reducing agent is equal to or higher than a predetermined temperature, it is determined that the reducing agent is warmed, and the flow rate of the hydraulic oil is reduced as the temperature T of the reducing agent increases. The flow rate of hydraulic oil is adjusted accordingly.
The controller 42 appropriately controls the reducing agent valve 12 under appropriate conditions based on the state of the engine 2 to adjust the amount of reducing agent injected from the injection nozzle 11.

<Action and effect>
Since the exhaust gas purification apparatus for a hydraulic work machine according to an embodiment of the present invention is configured as described above, it has the following operations and effects.

The reducing agent in the reducing agent tank 13 is compressed by compressed air supplied by the air compressor 21 and pushed out to the reducing agent supply passage 14.
At this time, if the controller 42 determines that the temperature T of the reducing agent detected by the temperature sensor 41 is equal to or lower than the predetermined temperature and the reducing agent is cold, the controller 42 sends an electrical signal to the hydraulic oil valve 32 to supply the hydraulic oil. The flow rate of the hydraulic oil supplied to the heater 31 is maximized, and the electric heater 33 is operated to warm the reducing agent. The warmed reducing agent is injected from the injection nozzle 11 provided in the muffler 6 with the injection flow rate controlled by the reducing agent valve 12.

When the controller 42 determines that the reducing agent temperature T is equal to or higher than the predetermined temperature and the reducing agent is warmed, the controller 42 stops the operation of the electric heater 33 and operates according to the reducing agent temperature T. The oil valve 32 is controlled to adjust the flow rate of the working oil supplied to the working oil heater 31 to control the temperature T of the reducing agent.
Therefore, since the hydraulic oil heater 31 and the electric heater 33 are provided in the reducing agent supply passage 14 and the heaters 31 and 33 are controlled by the controller 42, the temperature T of the reducing agent can be stably controlled. And since a reducing agent is injected in the upstream of the reduction catalyst 7 in the state heated stably, exhaust gas purification efficiency can be improved.

Further, since the reducing agent tank 13 is built in the hydraulic oil tank 4, the reducing agent is hardly affected by the outside air temperature, and the reducing agent can be prevented from freezing even in a cold region.
Further, since the reducing agent tank 13 is surrounded by the heat insulating material 15, the influence of the reducing agent on the outside air temperature can be further reduced, and the temperature of the working oil in the working oil tank 4 (oil temperature) can be reduced. The influence received can be reduced. Surrounding the reducing agent 13 with the heat insulating material 15 is particularly effective because there is no risk of excessive heating of the reducing agent when the oil temperature in the hydraulic oil tank 4 becomes too high.

[Others]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, the reducing agent is the urea aqueous solution. However, the reducing agent is not limited to this as long as it is for purifying exhaust gas, and may be ammonia water, for example.

Moreover, in the said embodiment, although the exhaust gas purification apparatus 1 is provided with the electric heater 33, it does not necessarily need to be provided with the electric heater 33. FIG.
Moreover, in the said embodiment, although the reducing agent tank 13 is surrounded by the heat insulating material 15, it does not need to be surrounded by the heat insulating material 15 especially.
In the above embodiment, the flow rate of the hydraulic fluid supplied to the hydraulic fluid heater 31 via the hydraulic fluid valve 32 is controlled by the controller 42. However, the flow rate is always constant without being controlled by the controller 42. May be supplied.

  In the above embodiment, the exhaust purification device mounted on the hydraulic excavator has been described. However, the exhaust purification device may of course be mounted on another hydraulic work machine such as a crane or a bulldozer.

It is a typical lineblock diagram showing the exhaust gas purification device of the hydraulic working machine concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust purification device 2 Engine 3A, 3B Hydraulic pump 4 Hydraulic oil tank 5 Exhaust pipe 6 Muffler 7 Reduction catalyst 11 Injection nozzle 12 Reducing agent injection amount control valve (reducing agent valve)
DESCRIPTION OF SYMBOLS 13 Reducing agent tank 14 Reducing agent supply path 15 Heat insulating material 21 Air compressor 22 Electric motor 23 Air tank 24 Air dryer 31 Hydraulic oil heater 32 Hydraulic oil flow control valve (Valve for hydraulic oil)
33 Electric heater 41 Temperature sensor 42 Controller (control means)

Claims (4)

An exhaust purification device for a hydraulic work machine having a hydraulic oil tank for storing hydraulic oil for operating the hydraulic work machine and a reducing agent tank for storing a reducing agent for exhaust purification of the engine,
A reduction catalyst built in the muffler of the engine;
An injection nozzle that injects the reducing agent toward the upstream side of the exhaust passage of the reduction catalyst;
A reducing agent supply passage for supplying the reducing agent from the reducing agent tank to the injection nozzle;
A hydraulic oil heater that warms the reducing agent by using the hydraulic oil that is interposed in the reducing agent supply passage and returns to the hydraulic oil tank;
An exhaust emission control device for a hydraulic work machine, wherein the reducing agent tank is built in the hydraulic oil tank. 2. The exhaust gas purification apparatus for a hydraulic working machine according to claim 1, wherein the reducing agent tank is surrounded by a heat insulating material. Temperature detecting means for detecting the temperature of the reducing agent in the reducing agent supply passage;
Control means for controlling the flow rate of the hydraulic oil supplied to the hydraulic oil heater,
The control means controls the flow rate of the hydraulic oil supplied to the hydraulic oil heater based on the temperature of the reducing agent detected by the temperature detection means. Exhaust purification equipment for hydraulic work machines. An electric heater interposed in the reducing agent supply passage;
4. The exhaust gas purification apparatus for a hydraulic working machine according to claim 3, wherein the control means operates the electric heater based on the temperature of the reducing agent detected by the temperature detection means.

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