FR3128907A1 - REDUCED POLLUTION STRAP-OVER TRACTOR AGRICULTURAL VEHICLE - Google Patents

Abstract

This straddle tractor-type agricultural vehicle comprises:– a chassis;– an internal combustion engine comprising an engine block (15) and an exhaust line mounted on the chassis; – a selective catalytic reduction system comprising:* a catalyst placed on the exhaust line so as to reduce the nitrogen oxides emitted by the engine during combustion;* a urea tank (22) incorporating a reducing agent nitrogen oxides; and* a pump (23) connected to the urea tank (22) and to the catalyst so as to transmit the reducing agent to the catalyst;the urea tank (22) being fixed to a tilting flap (24a) movably mounted on the frame between two positions:. an operational position in which the urea tank (22) is arranged close to the engine block (15), a thermally insulating wall (41) of the tilting flap (24a) being interposed between the urea tank (22) and the engine block (15); And. a maintenance position in which the urea tank (22) is moved away from the engine block (15) so as to be able to carry out maintenance operations on the engine block (15). Figure for abstract: Fig 2

Description

REDUCED POLLUTION STRAP-OVER TRACTOR AGRICULTURAL VEHICLE

Field of invention

The present invention relates to the technical field of agricultural vehicles, of the straddle tractor type, used for growing vines.

More specifically, the invention relates to an agricultural vehicle configured to progress between the rows of vines while carrying out various tasks, such as tilling the soil or the vines or even supporting the harvest of the grape pickers.

The invention finds a particularly advantageous application for reducing the pollution emitted by such an agricultural vehicle.

Prior state of the art

A high-clearance tractor is an agricultural vehicle with three or four wheels distributed over two axles. A frame connects the axles and forms an arch so as to span at least one row of vines. In addition, the frame is also configured to support tools for carrying out treatments on the vine or the ground, such as spraying treatments on the foliage, trimming, crushing of vine shoots on the ground...

To move the high-clearance tractor in the rows of vines, it comprises a motor fixed to the frame and intended to drive one or more axles. A driver's cabin is also mounted on the chassis and allows control of the engine and the orientation of at least one axle. Such high-clearance tractors are known in particular from documents FR 2547160 and FR 3097832.

Vineyard work is often carried out on steep and muddy ground, so the traction power of a high-clearance tractor must be adapted accordingly. It follows that high-clearance tractors today incorporate internal combustion engines and, more particularly, internal combustion engines, such as the diesel engine. In addition, to guarantee the compactness of the heat engine, it is conventionally necessary to use at least one turbocharger making it possible to increase the oxygen level in each cylinder of said engine by compressing the intake air. However, this turbocharger releases a large amount of heat, typically close to 550°C.

In addition, this type of engine rejects a certain number of pollutants, in particular nitrogen oxides. For the preservation of the vine and the environment, it is sought to limit the generation of these pollutants.

This environmental problem is exacerbated in the current context.

To limit the generation of pollutants, it is known in the field of agriculture to use tractors, the exhaust line of which incorporates a selective catalytic reduction system, also known by the acronym SCR for " selective catalytic reduction ". in Anglo-Saxon literature.

This selective catalytic reduction system comprises a catalyst placed on the exhaust line and carrying out redox redaction of the nitrogen oxides to transform them into dinitrogen N ₂ , water and carbon dioxide. To do this, the catalyst is fed with a reducing agent, called urea. Thus, the selective catalytic reduction system also comprises a urea tank and a pump connected to the urea tank and to the catalyst so as to transmit the reducing agent to the catalyst.

The urea tank must be easily accessible because the user must typically fill up with urea as many times as he fills up with fuel. Furthermore, to guarantee optimum operation of the selective catalytic reduction system, the reducing agent must be injected into the catalyst with a temperature close to that of the engine exhaust gases, that is to say of the order of 650 °C. Thus, the reducing agent is moved from the urea tank to an injector present on an exhaust duct while very precisely controlling its temperature. To do this, a hydraulic heat transfer circuit is conventionally used to heat the urea tank and the pump to a temperature close to that of the exhaust gases. The hydraulic hoses for conveying the reducing agent between the urea tank and the pump, and between the pump and the injector, are also heated, for example with resistive electric heating.

The selective catalytic reduction system must therefore, as far as possible, be protected from heat loss and protected from air flows that could ventilate it.

In addition, the heat from the selective catalytic reduction system requires placing the hydraulic hoses and electrical cables away from the selective catalytic reduction system or using thermal protection devices between the selective catalytic reduction system and these hoses or cables.

With all these constraints, it is possible to integrate a selective catalytic reduction system into conventional tractor engines, as described in EP 3604752.

The structure of high-clearance tractors nevertheless induces additional installation constraints. Indeed, the weight of the engine assembly must be limited as well as the size of the engine to limit the risk of overturning. In addition, it is also necessary to guarantee access to the engine to carry out maintenance operations.

Given the various constraints applied to the integration of a selective catalytic reduction system and to the engines of high-clearance tractors, there is not yet a high-clearance tractor allowing the integration of a selective catalytic reduction system.

The technical problem that the invention intends to solve therefore concerns the optimized integration of a selective catalytic reduction system in an agricultural vehicle of the straddle tractor type in order to reduce the pollution resulting from the use of the latter.

To address this technical problem, the invention proposes to position the urea tank in a retractable manner in front of the engine block so as to obtain an engine assembly with reduced bulk. In addition, to prevent the temperature variations of the engine and possibly of the turbocharger from causing undesired heating or cooling of the reducing agent, the urea tank is fixed on a tilting flap having a thermally insulating wall interposed between the urea tank and engine block.

However, positioning the urea tank in front of the engine block limits access to the engine for maintenance operations, and mounting the urea tank in a retractable manner solves this problem.

To this end, the invention relates to an agricultural vehicle of the straddle tractor type comprising:
- a chassis ;
– an internal combustion engine comprising an engine block and an exhaust line mounted on the frame; And
– a front axle and a rear axle mounted on the chassis; at least one axle being steered and at least one axle being driven by the engine.

The invention is characterized in that the agricultural vehicle also comprises a selective catalytic reduction system comprising:
– a catalyst placed on the exhaust line so as to reduce the nitrogen oxides emitted by the engine during combustion;
– a urea tank incorporating a nitrogen oxide reducing agent;
– a pump connected to the urea tank and to the catalyst so as to transmit the reducing agent to the catalyst;
– the urea tank being fixed on a tilting shutter mounted on the chassis between two positions:
* an operational position in which the urea tank is arranged close to the engine block, a thermally insulating wall of the tilting flap being interposed between the urea tank and the engine block; And
* a maintenance position in which the urea tank is removed from the engine block so as to be able to carry out maintenance operations on the engine block.

Preferably, the urea tank is arranged in contact with a support frame of the engine block in the operational position so as to limit the overall dimensions as much as possible, while protecting it with the thermally insulating wall.

According to one embodiment, the thermally insulating wall of the tilting flap, interposed between the urea tank and the engine block in the operational position, has two plates fixed by studs, the plates being separated by a distance of between 20 and 25 millimeters.

This embodiment makes it possible to obtain an air gap between the two plates so as to obtain a high thermal conductivity, of the order of 0.0262 Wm ^-2 K ^-1 . Thus, the pump and the urea tank can be positioned relatively close to the engine block, typically at a distance of between 45 and 55 millimeters. Contrary to other insulating materials which are often sensitive to humidity and high pressure washing, recurrent on this type of agricultural vehicle, the use of an air gap as thermal insulation makes it possible to obtain great durability and great resistance.

Typically, the mounts have anti-vibration properties so as to protect the pump and the urea tank from engine vibrations.

To obtain a retractable urea tank, it is preferably mounted on a tilting flap mounted on frame hinges. The tilting flap may include a lock to hold the urea tank in the operational position.

The pump can be mobile or fixed relative to the urea tank without changing the invention. For example, the pump can also be mounted on the tilting flap, the pump then being connected to the catalyst by at least one flexible cable. A flexible cable can also be used to connect the urea tank to the pump.

In all cases of assembly, pump and urea tank integral with the tilting shutter, or only urea tank integral with the tilting flap, the pump and the urea tank are connected by different hoses and cables. Indeed, the selective catalytic reduction system comprises hydraulic hoses for conveying the reducing agent from the urea tank to the pump and hydraulic hoses for conveying the reducing agent from the pump to an injector present on an exhaust pipe. In addition, heat transfer fluid lines are also used to heat the reducing agent when its temperature is too low. For example, this heat transfer fluid is likely to circulate at the level of the urea tank and the pump.

To detect heating needs of the reducing agent, temperature sensors can be installed on the urea tank and on the pump. Thus, the selective catalytic reduction system can also comprise a control member receiving the temperature information and applying the necessary heating means.

Preferably, a hydraulic heat transfer circuit is used to heat the urea tank and the pump to a temperature close to that of the exhaust gases. As a corollary, the hydraulic hoses for conveying the reducing agent between the urea tank and the pump, and between the pump and an injector, are also heated, for example with a resistive electric heater.

To protect the selective catalytic reduction system and the engine block, the agricultural vehicle preferably comprises a protective cover. Thus, to access the urea tank, it may be necessary to open the protective cover. The urea tank may have a filler cap so that filling the urea tank can be done by opening the protective cover and accessing the urea tank filler cap.

To simplify the filling of the urea tank, the urea tank may comprise a remote filling plug passing through an opening of the protective cover so as to guarantee accessibility to the urea tank for its filling.

In addition to the selective catalytic reduction system, the agricultural vehicle may also include other pollution control systems. For example, the agricultural vehicle can incorporate a catalytic converter. Within the meaning of the invention, a catalytic converter corresponds to a diesel oxidation catalytic converter, also called DOC for “ Diesel Oxidation Catalyst ” in the Anglo-Saxon literature, installed on the exhaust line. The exhaust line can also be equipped with a particle filter.

Indeed, the combination of a catalytic converter, a particle filter and a selective catalytic reduction system makes it possible to greatly limit polluting emissions and, thus, to protect the vine and the environment.

Brief description of figures

The invention will be well understood on reading the following description, the details of which are given solely by way of example, and developed in relation to the appended figures, in which identical references relate to identical elements:

There illustrates a schematic perspective view of a high-clearance tractor incorporating a selective catalytic reduction system according to a first embodiment of the invention;

There illustrates a partial schematic side view of the high-clearance tractor of the ;

There illustrates a schematic perspective view of the side of the high-clearance tractor of the in operational position;

There illustrates a schematic perspective view of the side of the high-clearance tractor of the in service position;

There illustrates a schematic front three-quarter perspective view of a high-clearance tractor incorporating a selective catalytic reduction system according to a second embodiment of the invention;

There illustrates a schematic rear three-quarter perspective view of a high-clearance tractor of the high-clearance tractor of the ;

There illustrates a partial schematic view from behind of the high-clearance tractor of the in operational position; And

There illustrates a schematic partial rear three-quarter perspective view of the high-clearance tractor of the in service position.

Claims (11)

Agricultural vehicle of the straddle tractor type (10a-10b) comprising:
– a frame (11a-11b);
– an internal combustion engine comprising an engine block (15) and an exhaust line mounted on the frame (11a-11b); And
– a front axle (12) and a rear axle (13) mounted on the frame (11a-11b); at least one axle (12-13) being steering and at least one axle (12-13) being driven by the engine;
characterized in that the agricultural vehicle (10a-10b) also comprises a selective catalytic reduction system comprising:
– a catalyst placed on the exhaust line so as to reduce the nitrogen oxides emitted by the engine during combustion;
– a urea tank (22) integrating a nitrogen oxide reducing agent; And
– a pump (23) connected to the urea tank (22) and to the catalyst so as to transmit the reducing agent to the catalyst;
the urea tank (22) being fixed on a tilting flap (24a-24b) mounted to move on the frame (11a-11b) between two positions:
* an operational position in which the urea tank (22) is arranged close to the engine block (15), a thermally insulating wall (41) of the tilting flap (24a-24b) being interposed between the urea tank (22 ) and the engine block (15); And
* a maintenance position in which the urea tank (22) is remote from the engine block (15) so as to be able to carry out maintenance operations on the engine block (15). Agricultural vehicle according to Claim 1, in which the thermally insulating wall (41) of the tilting flap (24a-24b), interposed between the urea tank (22) and the engine block (15) in the operational position, has two plates (35, 36) fixed by studs (40), the plates (35, 36) being separated by a distance of between 20 and 25 millimeters. Agricultural vehicle according to Claim 2, in which the studs (40) develop anti-vibration properties. Agricultural vehicle according to one of Claims 1 to 3, in which the tilting flap (24a-24b) is mounted on hinges (25) of the frame (11a-11b). Agricultural vehicle according to one of Claims 1 to 4, in which the tilting flap (24a-24b) comprises a lock (26) able to hold the urea tank (22) in the operational position. Agricultural vehicle according to one of Claims 1 to 5, in which the pump (23) is also mounted on the tilting flap (24a-24b), the pump (23) being connected to the catalyst by at least one flexible cable (31) . Agricultural vehicle according to one of Claims 1 to 6, in which the pump is connected to the urea tank (22) by at least one flexible cable (30). Agricultural vehicle according to one of Claims 1 to 7, in which the engine block (15) and the selective catalytic reduction system are protected by a protective cover (17a-17b). Agricultural vehicle according to Claim 8, in which the urea tank (22) comprises an offset filler cap (29) passing through an opening of the protective cover (17a-17b) so as to guarantee accessibility to the urea tank (22) for its filling. Agricultural vehicle according to one of Claims 1 to 9, in which the agricultural vehicle (10) incorporates a catalytic converter. Agricultural vehicle according to one of Claims 1 to 10, in which the agricultural vehicle (10) incorporates a particle filter.