CN104474834A - Fuel-oil steam adsorption method of automobile engine - Google Patents

Abstract

A disclosed fuel-oil steam adsorption method of an automobile engine comprises installing an adsorption device at one side of a fuel-tank oil pump and is characterized in that an adsorbent is a porous material containing a low-molecular-weight organic compound, and the average pore size of the material is 10-200 nm. The preparation method of the adsorbent comprises: dipping hydrophobic silica gel with the average pore size of 10-200 nm in an organic compound, drying the silica gel at 80-200 DEG C for 1-3 h. The 100% butane saturated adsorption amount of the adsorbent material at 25 DEG C is 50.5-80 g/mL, the volatile matter content at 200 DEG C is 2.2-5%, and the organic compound is one or more of octyl dodecanol, isostearyl alcohol, oleyl alcohol, 2-hexyl-1-decanol, 2-butyl-1-octanol and 2-undecyl pentadecanol. The adsorption capability in the method is strong.

Description

A kind of fuel vapor adsorption method of automobile engine

Technical field

The present invention relates to a kind of fuel vapor adsorption method of automobile engine.

Background technology

Adsorbent efficiency in a particular application, usually by adsorbent to the adsorption capacity of described adsorbate with selectively to determine.Adsorption capacity can be measured by the adsorbance of unit mass or unit volume adsorbent.

In general, adsorbent is to the adsorption capacity of specific adsorbate and selective higher, and it is more useful, because less adsorbent just can produce the same effect removing adsorbate.Carbonaceous material, as active carbon, carbon black, etc. be a kind of important adsorbent, it can be used for many occasions, as be separated, purify and refuse process, etc.Because carbonaceous material is of many uses, any method, as long as can improve the absorption property of carbon-bearing adsorbent to specific adsorbate, just can in efficiency and economically, have an immense impact on to adopting its technique.Therefore, the past has carried out some trials, in the hope of carrying out modification to the surface chemical property of carbon-bearing adsorbent.Method for these modifications can be divided into physics and chemistry method substantially.In the surface modification of physical method, a kind of electrodeposition substance is formed one deck on the surface of carbon-bearing adsorbent, then this layer just can change its absorption property.But this method of modifying is limited in practicality, because sedimentary deposit is easy to come off.In the surface modification of chemical method, modified material is connected on carbon surface by the mode of chemical bond.Absorption isotherm can represent under a fixed temperature, the correlation of degree of absorption and adsorbate concentration or adsorbate dividing potential drop, and therefore its characteristic is also important.If the people such as Sircar are described in " active carbon for gas separaion and storage " Carbon, Vol.34, № 1, pp.1-12 (1996), the characteristic of preferred absorption isotherm depends on separation method used.Such as, be stressed in the occasion of influence of change in the palingenesis of adsorbent, preferred adsorbent should have the affinity of appropriateness to adsorbate.If strong adsorption adsorbate, that is, when it has strong affinity to adsorbate, palingenesis becomes difficulty and produce power is intensive.On the other hand, when adsorbent has weak affinity to adsorbate, it divides the adsorption capacity of pressure just less at low adsorbent, and therefore, its quality of adsorption transition range just becomes very long.Therefore, obtaining a kind of is very useful for changing the method for adsorbent to adsorbate affinity.

Therefore, any method, as long as can improve adsorbent adsorption capacity and/or improve absorption affinity all can be used in adsorption applications.As has been noted, chemical modification can be used for the absorption property changing carbon-bearing adsorbent.But the scope of the chemical substance that can connect is limited.

Bansal, Donnet and Stoeckli (the 5th chapter of Active Carbon, Marcel Dekker, Inc., 1988) have commented various different carbon surface modification technology.Which describe object infusion process, these methods rely on carrys out modify carbon surfaces with the chemical reaction of various material.Some chemical surface modification methods described by the people such as Bansal have oxidation, halogenation, sulfonation and ammoniation.In these methods, several needs is had to carry out pyrocarbon process.Sircar and Golden (United States Patent (USP) № 4702749) describes another kind of method, comprising: in the presence of a catalyst, carry out carbonoxide material with HNO 3.But to one skilled in the art, these methods obviously have some defect.Because the chemical method of modified carbonaceous adsorbent surface is limited to some extent in practicality, therefore still need to develop a kind of carbon modified adsorbent, compared with unmodified material, the adsorption capacity of this carbon modified adsorbent is improved.

The emission regulation of current many countries requires that the EVAP effluent controlled in the fuel oil supply system of internal combustion engine of motor vehicle is discharged into the fuel amount in air to eliminate or to reduce kind vaporizer thus significantly.Therefore, the common practice installs a fuel-steam gathering-device under all conditions experienced at motor vehicle all thereon to adsorb the EVAP effluent in fuel oil supply system.This fuel-steam gathering-device is generally activated carbon class so-called " canister ".The operation principle of this kind of fuel-steam gathering-device is the physical absorption principle based on active carbon adsorption fuel-steam.Fuel-steam gathering-device has a finite volume storing fuel oil, and this device must by emptying for a part for its capacity in the motor vehicle course of work.The fuel oil gathered normally removes the air inlet pipe into engine by fuel-steam gathering-device under the attraction of air, and the fuel oil be eliminated is then by engine combustion.The fuel-steam amount removed from fuel-steam gathering-device can vary widely because of the change of the speed of any given removing air stream, and the ratio removing air stream depends on the saturation degree in fuel-steam gathering-device.Because (usually known open cycle system) that the amount of the fuel oil be eliminated normally is not measured in the system not having air/fuel feedback mechanism, engine control system can not compensate its fuelling rate increased.This will cause the increase of engine torque, and when causing the race of engine (idling), the too high or motor vehicle of rotating speed departs from idle running hourly velocity increases.In severe cases, engine operation becomes unstable, because Air/Fuel Ratio actual in cylinder is different from the Air/Fuel Ratio mapped by engine control system widely.

Process a scheme of this problem described in the United States Patent (USP) of No. 5245974 of applicant.This file illustrates the internal combustion engine with fuel-steam gathering-device, and this fuel-steam gathering-device is used for removing fuel-steam the EVAP effluent produced from fuel oil supply system.Engine comprises a fuel injection system and is with one to provide compressed-air actuated air compressor to fuel injection system.The compressed air that fuel-steam gathering-device air compressor produces clears away the fuel oil gathered periodically by fuel-steam gathering-device.Air compressor provides compressed air to carry fuel oil and enters fuel injection system, and the combustion chamber that then air sprays into engine makes the fuel oil by cleaning produce burning.Although add by injector the fuel oil be eliminated, the large portion of the stratification phenomena in cylinder is remained unchanged, this patent does not discuss the problem of not knowing the amount of fuel that fuel-steam gathering-device provides especially.There is provided one can control to optimize by the air rate of fuel-steam gathering-device the amount of fuel removed from fuel-steam gathering-device and the work not jeopardizing engine is favourable.Consider these situations, the object of this invention is to provide a kind of improve one's methods and control system be used for control by the air rate in fuel of internal combustion engine vapor collecting apparatus.Provide a kind of method for controlling the fuel delivery from vapor collecting apparatus to combustion chambers of internal combustion engines, the removing stream that utilization flows to engine from vapor collecting apparatus removes the fuel oil accumulated in vapor collecting apparatus, the flow rate removing stream is transformable, it regulates by means of a flow control valve between vapor collecting apparatus and engine, the method comprises determines a minimum valve signal value and a maximal valve signal value, they are functions of engine loading and rotating speed, thus determine the aperture of degree for control valve of minimum and maximal valve signal value respectively, amount of fuel into engine is removed from vapor collecting apparatus in order to optimize under the condition of work that changes at engine, the interpolation between minimum and maximal valve signal value or minimum and maximum value is selected according to the condition of work of engine.This method at least can make fuel-steam gathering-device remove continuously basically, the amount of fuel being drained into engine from the purification of fuel-steam gathering-device can be made to be optimized and for the condition of work of engine variable.

This fuel-steam gathering-device can communicate with of an engine air inlet pipe, so the method can control the amount of fuel entering air inlet pipe.Pressure differential between fuel-steam gathering-device and air inlet pipe can be enough large, makes air enter into air inlet pipe by fuel-steam gathering-device.This method can be used for other schemes equally, such as above-mentioned in the purification of the patent No. described in the United States Patent (USP) of 5245974 by an air compressor.The method can realize with a vario valve and a control device, and vario valve controls from the air rate of fuel-steam gathering-device, and control device is used for the function of control valve as engine condition.Control device can be that electronic control unit form (ECU) is carried out gradually opening of control valve for the valve signal value be supplied to needed for valve and gradually closes.A given valve signal may correspond in a given valve position.

ECU can comprise at least two and map for " the searching " mapping (correspondence) valve signal value, and valve signal value is for controlling the function of this valve as engine condition.Each searches mapping and can provide corresponding to the valve signal value in each circulation oil consumption (FPC) and engine speed (RPM) coordinate system.One of mapping can be that one " minimum " maps, valve signal value when it needs to be floor level to the removing air mass flow that should flow into engine.Time this situation such as occurs in and is rich in fuel-steam the air of discharging from vapor collecting apparatus.Another mapping can be that one " maximum " maps, valve signal value when it is maximum to the removing air mass flow that should flow into engine.This considers following situation, when removing the Air/Fuel Ratio of air and being lower and engine operation under medium and high load condition.Thus minimum and maximum mapping can limit the minimum of valve signal value and maximum magnitude respectively for the openings of sizes of control valve and control to remove the flow rate of air, and the opening of valve increases gradually along with the increase of valve position value.Valve signal value can from two map any one obtain or according to engine condition two map between interpolation obtain.Interpolation number is provided by an adaptation value.Adaptation value can be provided by an arbitrary value system, produces a total value determination valve position according to given condition arbitrary value system assignment is minimum with ratio that is maximum.This adaptation value scope is that 0.0 to 1.0,0.0 value is answered with minimum mapping pair, and 1.0 values should with maximum mapping pair.

Adaptation value searches the function mapping and adaptation value can be mapped as engine coolant temperature.Ato unit for the first time, water temperature can be measured and initial adaptation value obtains from mapping adaptation value.If this guarantees engine is once starting heating, adaptation value can be lower to limit the flowing of removing air.Under thermal starting condition, relatively a large amount of fuel-steams can be produced in fuel tank, then be adsorbed in fuel-steam gathering-device.Valve position is followed thermal starting and too much fuel oil therefore can be prevented at this moment to be eliminated.

Automobile exhaust gas and industrial waste gas (such as producing because organic solvent in paint industry evaporates in dry run) become environmental problem.Thus need effectively to reclaim this organic gas.The fuel used gasoline of automobile is high-volatile.Therefore, when automobile runs or when parking, gasoline evaporates in fuel tank under the scorching hot sun, and gasoline vapour is discharged in air.Also gasoline vapour is produced in refueling process.

Therefore, in order to prevent gasoline vapour from discharging from automobile, provide filter tank in the car, and the active carbon etc. be contained in filter tank is used as absorber material.Such as, Japanese Patent Publication (Kokai) 2005-35812A points out, be adsorbed on by making organic substance and have on the initial activity charcoal of wide region pore size, the hole making aperture little is by optionally shutoff, then obtained active carbon has excellent adsorption/desorption character.Patent document 1 also illustrates and uses the filter tank of this active carbon to inhibit to be revealed by adsorption component.

But, have developed such as, for adsorbing and removing the porous material with hole of organic gas, active carbon, and come into operation.It is reported, the adsorption mechanism of this organic gas is that organic gas is under high pressure liquefied in the micropore of porous material, and is retained by being adsorbed in micropore.

Therefore, the pore size of sorbent material is optimized according to the molecular weight, concentration etc. of organic gas upon adsorption.In order to adsorb the organic gas of lower molecular weight, such as butane, to have a large amount of diameters be the porous material of the micropore of 5nm or less is preferred.On the contrary, for having the porous material that diameter is the macropore of 10nm or larger, organic gas is difficult under high pressure liquefy in hole, and thus low-molecular-weight gas is not just retained by absorption.

The sorbent material that Japanese Patent Publication (Kokai) 2005-35812A describes employs and looks the active carbon of mean pore size close to 2 to 5nm.But, wherein do not use and there is mean pore size for the porous material absorption of the macropore of about 10 to 200nm or the embodiment absorbing low-molecular-weight organic gas.

Summary of the invention

The object of the invention is to the fuel vapor adsorption method proposing a kind of automobile engine.

For reaching this object, the present invention by the following technical solutions:

A kind of fuel vapor adsorption method of automobile engine, method comprises: install adsorbent equipment in fuel tank oil pump side, adsorbent is for comprising low-molecular-weight organic porous material, its mean pore size is 10 to 200nm, its preparation method is: be that the dewatering silica gel of 10 to 200nm floods in organic compound by mean pore size, at 80-200 DEG C by this silica dehydrator 1-3 hour, absorber material is 50.5-80g/ml at the 100% butane saturated extent of adsorption of 25 DEG C, volatile content 200 DEG C time is 2.2-5%, described organic compound is octyldodecanol, isooctadecanol, oleyl alcohol, 2-hexyl decyl alcohol, one or more in 2-butyl octanol and 2-undecyl pentadecane alcohol.

Low-molecular-weight gas is utilized to be dissolved in the dissolution of organic solvent, the present inventor finds, by adhering to and/or flooding the organic substance with higher molecular weight, low-molecular-weight organic gas even dissolve in tool eurypyloue, usually can not adsorb in the porous material of low-molecular-weight organic gas (such as butane etc.).As a result, low-molecular-weight organic gas is eliminated by absorption.Therefore, this material can be used as effective low-molecular-weight organic gas absorber material

Detailed description of the invention

Embodiment 1

A kind of fuel vapor adsorption method of automobile engine, method comprises: install adsorbent equipment in fuel tank oil pump side, it is characterized in that adsorbent is for comprising low-molecular-weight organic porous material, its mean pore size is 10 to 200nm, its preparation method is: be that the dewatering silica gel of 10 to 200nm floods in organic compound by mean pore size, at 80-200 DEG C by this silica dehydrator 1-3 hour, absorber material is 50.5-80g/ml at the 100% butane saturated extent of adsorption of 25 DEG C, volatile content 200 DEG C time is 2.2-5%, described organic compound is octyldodecanol, isooctadecanol, oleyl alcohol, 2-hexyl decyl alcohol, one or more in 2-butyl octanol and 2-undecyl pentadecane alcohol.

Obviously, the above embodiment of the present invention is only for example of the present invention is clearly described, and is not the restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all embodiments.And these belong to spirit institute's apparent change of extending out of the present invention or change and are still among protection scope of the present invention.

Claims (1)

1. the fuel vapor adsorption method of an automobile engine, method comprises: install adsorbent equipment in fuel tank oil pump side, it is characterized in that adsorbent is for comprising low-molecular-weight organic porous material, its mean pore size is 10 to 200nm, its preparation method is: be that the dewatering silica gel of 10 to 200nm floods in organic compound by mean pore size, at 80-200 DEG C by this silica dehydrator 1-3 hour, absorber material is 50.5-80g/ml at the 100% butane saturated extent of adsorption of 25 DEG C, volatile content 200 DEG C time is 2.2-5%, described organic compound is octyldodecanol, isooctadecanol, oleyl alcohol, 2-hexyl decyl alcohol, one or more in 2-butyl octanol and 2-undecyl pentadecane alcohol.