JP5054613B2 - Engine exhaust gas purification device - Google Patents

Description

  The present invention relates to an exhaust gas purification device for an engine mounted on a vehicle, particularly a short vehicle, and more specifically, the exhaust gas purification device reduces and purifies nitrogen oxide (NOx) in exhaust gas using a liquid reducing agent. The present invention relates to an arrangement of an exhaust gas purification device in a vehicle.

As a means for purifying exhaust gas of an engine mounted on a vehicle, a selective reduction type NOx catalyst system that reduces NOx to nitrogen by injecting a mixture of urea aqueous solution and compressed air upstream of the selective reduction type NOx catalyst ( SCR (Selective Catalytic Reduction) is adopted.
Such an exhaust gas purification device injects a required amount of liquid reducing agent according to the engine operating state to the exhaust upstream side of the reduction catalyst disposed in the exhaust pipe of the engine, so that NOx in the exhaust gas and the liquid reducing agent are injected. And NOx are purified into harmless components by a catalytic reduction reaction.
The reduction reaction uses ammonia that has good reactivity with NOx, and as the liquid reducing agent, an aqueous urea solution that generates ammonia by hydrolysis with exhaust heat and water vapor in exhaust gas is used.

Patent Document 1 (Japanese Patent Laid-Open No. 2005-273578) discloses an in-vehicle exhaust gas purifying apparatus using such a system. An exhaust gas purification device disclosed in Patent Document 1 (FIG. 1) will be described with reference to FIG.
In FIG. 6, an exhaust pipe 014 connected to the exhaust manifold 012 of the engine 010 has an oxidation catalyst 016 that oxidizes nitrogen monoxide (NO) to nitrogen dioxide (NO ₂ ) along the exhaust gas flow direction, An injection nozzle 018 that injects an aqueous urea solution, an NOx reduction catalyst 020 that reduces and removes NOx with ammonia obtained by hydrolyzing the aqueous urea solution, and an ammonia oxidation catalyst 022 that oxidizes ammonia that has passed through the NOx reduction catalyst 020. Each is arranged.

  An aqueous urea solution stored in the reducing agent tank 024 is supplied to the injection nozzle 018 in a sprayed state mixed with air via the reducing agent supply device 026. Here, the reducing agent supply device 026 is controlled by a control unit 028 having a built-in computer, and supplies a required amount of urea aqueous solution according to the engine operating state to the injection nozzle 018 while mixing with air.

The aqueous urea solution injected from the injection nozzle 018 is hydrolyzed by exhaust gas heat and water vapor in the exhaust gas to generate ammonia. The generated ammonia reacts with NOx in the exhaust gas in the NOx reduction catalyst 020 and is purified into water and harmless gas. At this time, in order to improve the NOx purification rate by the NOx reduction catalyst 020, NO is oxidized to NO ₂ by the oxidation catalyst 016, improvements to what ratio between NO and NO ₂ in the exhaust gas is suitable for the catalytic reduction reaction Is done. The ammonia that has passed through the NOx reduction catalyst 020 is oxidized by the ammonia oxidation catalyst 022 disposed on the downstream side of the exhaust gas, and ammonia that emits a strange odor is prevented from being discharged into the atmosphere as it is.

As described above, the exhaust gas purifying apparatus that employs the SCR system includes the reducing agent tank 024, the reducing agent supply apparatus 026, and the like. When the SCR system is employed in an in-vehicle engine, it is necessary to mount these devices on the vehicle. There is.
However, in a large vehicle such as a truck, the reducing agent tank becomes large, and it is difficult to secure a place to attach it. Therefore, in Patent Document 1, a reducing agent tank is attached to the outer side in the vehicle width direction of a leaf spring used as a suspension device. The reducing agent tank is tiltably attached, and when the leaf spring is inspected or replaced, the reducing agent tank is tilted to facilitate the work of attaching and detaching the spring pin fitted to the spring eye.

  Japanese Patent Application Laid-Open No. 2006-321368 discloses a configuration in which an SCR system is applied to a snow removal truck. Since the snow removal track has a snow removal grader between the front and rear wheels, it is necessary to have a layout that avoids interference between the exhaust system including the SCR system and the grader bracket that holds the snow removal grader via multiple cylinders. There is.

  Therefore, in Patent Document 2, the muffler is disposed on the front side of the grader, the urea injection device is supported at a position where the interference with the grader bracket can be avoided above the muffler, and the NOx reduction catalyst is provided in the muffler. A urea sprayer and a temperature sensor are attached to the muffler, and a cover is provided to protect the piping and wiring interposed between the muffler and the urea injection device from adhesion or accumulation of snow or the like.

JP 2005-273578 A JP 2006-321368 A

In Patent Document 1, the reducing agent tank is attached between the front wheel and the fuel tank. With this arrangement, in the case of a short vehicle, the clearance between the front wheel and the fuel tank is small, and a mounting place for the reducing agent supply device is secured. Is difficult. Moreover, in order to attach a large reducing agent tank so as to be tiltable, there is a problem that the mounting structure is complicated.
Moreover, in patent document 2, the distance between the urea spray device provided in the muffler and the urea sprayer and temperature sensor becomes long, and the hose and wiring of urea aqueous solution which connect between these apparatuses become long. Therefore, it takes time to install these pipes and wires.

  In addition, since the diameter of the urea aqueous solution hose has an upper limit, when the hose length increases, the pressure loss of the urea aqueous solution flowing through the hose occurs, the flow of the urea aqueous solution deteriorates, and the urea aqueous solution provided in the urea injection device There is a problem that the power of the supply pump increases.

  On the other hand, in short vehicles such as dump trucks and garbage trucks (for example, the distance between the wheel bases is 3 m or outside), it is necessary to install PTO equipment such as hydraulic equipment and a link mechanism that lifts and lowers the cargo bed. It is more difficult to arrange devices such as a supply device and a reducing agent tank around the side frame.

  In view of the problems of the prior art, the present invention makes it possible to mount the devices constituting the SCR system on a vehicle even in a short vehicle such as a dump truck, a mixer, and a garbage truck, and without increasing the number of parts. The purpose is not to affect the layout of the equipment.

In order to solve the above problems, an exhaust gas purifying apparatus for an engine according to the present invention comprises:
A pair of left and right side frames extending in the longitudinal direction of the vehicle;
A NOx catalyst provided in an exhaust pipe of an engine mounted on a vehicle;
An injection nozzle provided on the exhaust gas upstream side of the NOx catalyst and capable of injecting a reducing agent toward the NOx catalyst;
In an exhaust gas purifying apparatus for an engine comprising a reducing agent supply device for supplying a reducing agent to the injection nozzle,
The reducing agent supply device is fixed to a bracket for fixing a fuel filter unit, and the bracket is attached to an outer surface of the side frame. The bracket includes two side plates and a horizontal plate, and the reducing agent supply device is Fixed to the side frame side of the side plate,
An end of each side plate opposite to the side frame forms a bent portion that is bent inward, and the horizontal plate is installed between the side plates just inside the bent portion, and the fuel filter unit is mounted. It comprises a horizontal plate body in which an insertion hole for locking is formed, and a surrounding piece formed integrally with three sides of the horizontal plate body, and the surrounding piece surrounds the side plate and the bent portion from the outside. In this state, it is joined to the side plate and the bent portion.

In the device of the present invention, an existing bracket for fixing the fuel filter unit is used for the reducing agent supply device, and by fixing to the bracket, a new bracket is unnecessary and a mounting space is secured. Conventionally, the bracket for fixing the fuel filter unit is short in the vehicle width direction and forms a dead space outside in the vehicle width direction.
In the present invention, the reducing agent supply device is arranged in parallel with the bracket, so that it is not necessary to utilize this dead space and to secure another space. In addition, by using the existing brackets in parallel, the number of parts and fixing points are reduced, and the assembly work is facilitated.

In addition, the filter built in the fuel filter unit and the reducing agent supply device needs to be inspected and replaced at least once a year, but by fixing the fuel filter unit and the reducing agent supply device to the same bracket, These inspection and replacement operations are facilitated.
In addition, since no other equipment is disposed below the bracket, the reducing agent does not cause a trouble when the filter is replaced.

In the device of the present invention, the bracket may be disposed between the front wheel and a fuel tank attached to the outer surface of the side frame. By disposing the bracket to which the fuel filter and the reducing agent supply device are fixed at this position, the fuel filter and the fuel tank can be disposed close to each other, and the fuel pipe connecting the fuel filter and the fuel tank can be shortened. Piping can be easily constructed, and pressure loss of fuel passing through the fuel piping can be reduced.
In addition, since it is not necessary to leave a space near the rear wheel for the reducing agent supply device, it is not necessary to consider rearranging existing equipment arranged near the rear wheel.

In the apparatus of the present invention, the bracket has a hat-shaped shape in which a horizontal cross-sectional shape opens toward the vehicle inner side and the opening edge is attached to the outer side surface of the side frame, and the reducing agent is supplied into the hat-shaped shape. The device should be fixed.
By making the bracket for fixing the fuel filter and the reducing agent supply device into a hat shape, the bracket can be made highly rigid, and vibration of the reducing agent supply device can be suppressed. Further, the bracket can be firmly coupled to the side frame via the hat-shaped flange. Furthermore, since the reducing agent supply device is surrounded by the vertical wall of the hat-shaped bracket, the reducing agent supply device can be protected from stepping stones and the like.

In the device of the present invention, a bracket for fixing the fuel filter and the reducing agent supply device is disposed between the front wheel attached to the outer side surface of the side frame and the fuel tank, and the vertical direction of the bracket to which the reducing agent supply device is fixed. It is preferable to arrange the wall so that the side frame outer surface side is higher upward than the vehicle width direction outer side, and the fixing position of the reducing agent supply device is higher than the fuel tank.
As a result, when the leaf spring used as a suspension device located inside the bracket in the vehicle width direction is inspected or replaced, the lower part of the reducing agent supply device does not get in the way, so that the shackle pin fitted to the spring eye is attached and detached. Can be easily done.

  In addition to the above configuration, a reducing agent tank may be provided with the reducing agent supply device and the fuel tank interposed therebetween, and a reducing agent supply pipe connecting the reducing agent supply device and the reducing agent tank may be disposed above the fuel tank. In order not to stagnate the flow of the reducing agent flowing through the reducing agent supply pipe connecting the reducing agent supply device and the reducing agent tank, the height difference between them can be made substantially equal.

  In addition, the space above the fuel tank can be used effectively, the reducing agent supply piping can be shortened, and the pressure loss of the reducing agent passing through the reducing agent supply piping can be reduced. Further, since the bent portion of the reducing agent supply pipe can be eliminated and the substantially straight line can be formed, it is easy to process and attach the reducing agent supply pipe, and the pressure loss of the fuel flowing through the reducing agent supply pipe can be reduced. .

  In this invention apparatus, it is good to arrange | position a fuel filter unit inside a vehicle width direction inside the said bracket, and arrange | position a reducing agent supply apparatus inside a fuel filter unit. It is necessary to replace the filter built in the fuel filter unit once or twice a year. At this time, since air enters a plurality of hoses connected to the filter, it is necessary to perform a pumping operation for venting the hoses. It is in. By disposing the fuel filter unit inside the bracket on the outer side in the vehicle width direction, the filter replacement work can be facilitated.

  According to the present invention, a pair of left and right side frames extending in the vehicle front-rear direction, a NOx catalyst provided in an exhaust pipe of an engine mounted on the vehicle, provided on the exhaust gas upstream side of the NOx catalyst, In an exhaust gas purification apparatus for an engine comprising an injection nozzle capable of injecting a reducing agent toward the injection nozzle and a reducing agent supply device for supplying the reducing agent to the injection nozzle, the fuel filter unit is fixed to the reducing agent supply device Fixing to the bracket and attaching the bracket to the outer surface of the side frame eliminates the need for a new mounting space, enabling the equipment that constitutes the SCR system to be mounted on the vehicle even for short vehicles. At the same time, by using the existing brackets in parallel, the number of parts and the fixing points are reduced, and the assembly work becomes easy.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified.

  FIG. 1 is an overall configuration diagram in plan view of a short vehicle 1 such as a dump truck, a mixer, and a garbage truck. In FIG. 1, the short vehicle 1 has a pair of left and right side frames 12a and 12b arranged in parallel to the longitudinal direction of the vehicle behind the cabin 10. A pair of left and right front wheels 14a and 14b are disposed below the cabin 10, a pair of left and right rear wheels 16a and 16b are disposed behind, and a differential device 17 is disposed between the left and right side frames. On the position side of the left side frame 12b, an installation space 18 unique to various short vehicles is secured, and the installation space 18 is provided with hydraulic equipment and PTO equipment.

  A tool box 19 is fixed to the front side of the rear wheel 16b outside the left side frame 12b. A bracket 20, a fuel tank 22, and a reducing agent tank 24 for fixing the fuel filter unit and the reducing agent supply device are fixed to the outer surface of the side frame 12b between the cabin 10 and the tool box 19 in order from the front. A reducing agent such as an aqueous urea solution is supplied from a reducing agent supply device to a reducing agent injection nozzle provided in an engine exhaust pipe (not shown).

Next, the structure of the bracket 20 and the reducing agent tank 24 will be described with reference to FIGS. 2 and 3, a bridge 26 is provided adjacent to the rear end 10a of the cabin 10 so as to straddle the pair of left and right side frames 12a and 12b. The rear end 10a of the cabin 10 that can be tilted is attached to the bridge 26 and fixed.
A bracket 20 is fixed to the outer surface of the left side frame 12b adjacent to the cabin rear end 10a, and a fuel filter unit 28 and a reducing agent supply device 30 are fixed to the bracket 20. The reducing agent supply device 30 incorporates a pump for feeding the reducing agent, a filter for removing impurities contained in the reducing agent, and the like.

  On the rear side of the bracket 20, a fuel tank 22 and a reducing agent tank 24 are fixed to the outer surface of the left side frame 12b in this order. In the space above the fuel tank 22, reducing agent supply pipes 32 a, 32 b, and 32 c that connect the reducing agent supply device 30 and the reducing agent tank 24 are disposed. The reducing agent tank 24 is fixed to the outer surface of the side frame 12b via a bracket 34.

  4 and 5, a bracket 20 is a flange formed by bending a pair of side plates 20a and 20b arranged at intervals in the longitudinal direction of the vehicle and side frame side end portions of the side plates 20a and 20b by 90 degrees. 20c and 20d, the side plates 20a and 20b are bent at the other end by 90 degrees, and the side plates 20a and 20b are installed between the side plates 20a and 20b immediately inside the bent portions 20f and 20g. And a horizontal plate 20h connected to each other to form a hat shape.

  Enclosed pieces are integrally formed on the three sides of the horizontal plate 20h so as to be bent 90 degrees downward from the horizontal plate main body and cover the side plates 20a, 20b and the bent portions 20f, 20g from the outside. The surrounding pieces are joined to the side plates 20a, 20b and the bent portions 20f, 20g to maintain the support strength of the fuel filter unit 28.

  The side plates 20a and 20b have side frame side ends that form an opening 20e, the flange 20c is fixed to the outer surface of the left side frame 12b, and the flange 20d is a square cross-sectional shape fixed to the outer surface of the side frame 12b. Are fixed to the outer peripheral surface of the support column 36 (fixed portion of the bridge 26 to the side frames 12a and 12b). A circular hole 20i into which the fuel filter unit 28 is fitted is formed in the horizontal plate 20h.

  Then, the fuel filter unit 28 is inserted into the hole 20i, and the flange 28a formed integrally with the fuel filter unit 28 is locked to the horizontal plate 20h. In this state, the fuel filter unit 28 is fixed to the bracket 20 by connecting the flange 28a to the horizontal plate 20h with bolts through the bolt holes 28b and 28c.

  The reducing agent supply device 30 is fixed to the side plate 20b by three bolt connections (not shown). The side plates 20a and 20b are extended in the vicinity of the outer side surface of the left side frame 12b in the vertical direction as compared with the outer side in the vehicle width direction as shown by reference numeral A in FIG. is doing. The reducing agent supply device 30 is attached to the upper part of the side plate 20 b, so that the reducing agent supply device 30 can be disposed at a higher position above the fuel tank 22.

  In the present embodiment having such a configuration, the fuel filter unit 28 and the reducing agent supply device 30 are fixed to the bracket 20, the fuel filter unit 28 is disposed on the outer side in the vehicle width direction, and the reducing agent supply device 30 is connected to the fuel filter. Since the unit 28 is disposed on the inner side in the vehicle width direction, the bracket 20 can be formed in a shape elongated in the vehicle width direction without taking up space in the vehicle longitudinal direction. As a result, the reducing agent supply device 30 can be mounted on the vehicle without changing the arrangement space of the existing on-vehicle equipment.

Further, since the reducing agent supply device 30 is fixed to the bracket by using the existing bracket for fixing the fuel filter unit 28, a new bracket is unnecessary, the number of parts can be reduced, and the assembling work is facilitated. be able to.
In addition, since no other equipment is disposed below the bracket 20, even if the reducing agent leaks when the filter is replaced, there is no particular problem.

Further, the filter 29 built in the lower part of the fuel filter unit 28 and the filter 31 built in the reducing agent supply device 30 need to be inspected and replaced at least once a year. Fixing the agent supply device 30 to the same bracket 20 facilitates these inspection and replacement operations.
In addition, since no other equipment is disposed below the bracket 20, even if the reducing agent leaks during filter replacement or the like, there is no particular problem.

  Further, since the bracket 20 is disposed between the left front wheel 14b and the fuel tank 22, the fuel filter unit 28 and the fuel tank 22 can be disposed close to each other, and the fuel pipe connecting the fuel filter unit 28 and the fuel tank 22 is shortened. In addition, the fuel pipe can be easily installed and the pressure loss of the fuel passing through the fuel pipe can be reduced.

  Moreover, the bracket 20 can be made highly rigid by making the bracket 20 into a hat shape comprising the side plates 20a and 20b, the flanges 20c and 20d, the bent portions 20f and 20g, and the horizontal plate 20h. 30 vibrations can be suppressed. Further, the bracket can be firmly coupled to the side frame 12b via the flanges 20c and 20d. Furthermore, since the reducing agent supply device 30 is surrounded by the side plates 20a and 20b, the reducing agent supply device 30 can be protected from stepping stones and the like.

  Further, the side plates 20a and 20b of the bracket 20 to which the reducing agent supply device 30 is fixed are formed so as to be wide in the vertical direction, and are disposed higher above, so that the fixing position of the reducing agent supply device 30 is higher than the fuel tank unit 28. Since it is arranged higher, it can be arranged at substantially the same height as the reducing agent tank 24 is fixed, and at the time of inspection or replacement of a leaf spring used as a suspension device located on the front side of the bracket 20, the reducing agent supply device 30. The bottom of is not disturbed. Therefore, the attachment / detachment work of the shackle pin fitted to the spring eye can be facilitated.

Further, a reducing agent tank 24 is provided with the fuel tank 22 interposed between the reducing agent supply device 30 and reducing agent supply pipes 32 a to 32 c connecting the reducing agent supply device 30 and the reducing agent tank 24 are arranged above the fuel tank 22. Therefore, the space above the fuel tank 22 can be used effectively, the reducing agent supply pipe can be shortened, and the pressure loss of the reducing agent passing through the reducing agent supply pipe can be reduced.
Further, since the bent portions of the reducing agent supply pipes 32a to 32c can be eliminated so as to be substantially linear, the processing and mounting of the reducing agent supply pipe are facilitated, and the fuel flowing through the reducing agent supply pipe is reduced. Pressure loss can be reduced.

  In addition, since the fuel filter unit 28 is disposed outside the vehicle width direction inside the bracket 20 and the reducing agent supply device 30 is disposed inside the fuel filter unit, the filter built in the fuel filter unit 28 is arranged. Replacement work can be facilitated.

  According to the present invention, even in a short vehicle such as a dump truck, a mixer, a garbage truck, etc., it is possible to mount the equipment constituting the SCR system on the vehicle, and without increasing the number of parts, the arrangement of other equipment It becomes possible to install without changing.

1 is a plan view overall configuration diagram of a short wheel according to an embodiment of the present invention. FIG. 3 is a partially enlarged plan view according to the embodiment. It is a partially expanded side view which concerns on the said embodiment. It is a perspective view of the reducing agent supply device fixing bracket according to the embodiment. It is a side view of the reducing agent supply device fixing bracket according to the embodiment. It is a block diagram which shows the component apparatus of an SCR system.

Explanation of symbols

014 Exhaust pipe 018 Injection nozzle 020 NOx reduction catalyst 1 Short wheel 10 Cabin 12a, 12b Side frame 14a, 14b Front wheel 16a, 16b Rear wheel 20 Bracket 20a, 20b Side plate 20c, 20d Flange 20e Opening 22 Fuel tank 24 Fuel tank 24 Fuel Filter unit 30 Reducing agent supply device 32a to c Reducing agent supply piping A Bracket side plate extension

Claims (5)

A pair of left and right side frames extending in the longitudinal direction of the vehicle;
A NOx catalyst provided in an exhaust pipe of an engine mounted on a vehicle;
An injection nozzle provided on the exhaust gas upstream side of the NOx catalyst and capable of injecting a reducing agent toward the NOx catalyst;
In an exhaust gas purifying apparatus for an engine comprising a reducing agent supply device for supplying a reducing agent to the injection nozzle,
Fixing the reducing agent supply device to a bracket for fixing a fuel filter unit, and attaching the bracket to the outer surface of the side frame ;
The bracket comprises two side plates and a horizontal plate,
The reducing agent supply device is fixed to the side frame side of the side plate,
The end of each of the side plates opposite to the side frame forms a bent portion that is bent inward,
The horizontal plate is constructed between the side plates just inside the bent portion, and is formed integrally with a horizontal plate main body in which an insertion hole for locking the fuel filter unit is formed, and three sides of the horizontal plate main body. Consisting of a formed enclosure,
The engine exhaust gas purification apparatus , wherein the surrounding piece is joined to the side plate and the bent portion in a state of surrounding the side plate and the bent portion from the outside . The bracket, the exhaust gas purifying device for an engine according to claim 1, characterized in that disposed between the fuel tank mounted on the outer surface of the front wheel side frame. It said bracket is open toward the side the vehicle is horizontal cross section, forms a hat-shaped opening edge is attached to the outer surface of the side frame,
The exhaust gas purifying device for an engine according to claim 1 or 2, wherein the reducing agent supply device is fixed inside the hat shape. Before Symbol increased above the longitudinal dimension of the vehicle width direction outer side of the side frame outer side of the side plate of the bracket,
The reducing agent exhaust gas purification apparatus for an engine according to claim 2 in which the fixing position of the supply device, characterized in that it has placed above said fuel tank.   5. The reducing agent tank is provided with the reducing agent supply device and the fuel tank sandwiched therebetween, and a reducing agent supply pipe connecting the reducing agent supply device and the reducing agent tank is disposed above the fuel tank. Engine exhaust gas purification device.

Images