Patent Publication Number: US-7905137-B2

Title: Engine oil consumption measurement device and engine oil consumption measurement method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine oil consumption measurement device and an engine oil consumption measurement method. 
     2. Description of the Related Art 
     Conventionally, a gravimetric method, withdrawal method or the like are known as engine oil consumption measurement methods of an engine. However, conventional engine oil consumption measurement methods such as the gravimetric method and the withdrawal method have the following problems. They require a long period of time for measurement, engine oil is diluted by fuel or water that mixes with the engine oil at the time of measurement, and the engine oil consumption measured is lower than an actual amount. Thus, the accurate measurement of engine oil consumption is difficult. 
     In view of these problems, as a method allowing relatively accurate measurement of the engine oil consumption in a short time, a so-called S trace method has been disclosed (refer to JP-A-Hei 6-93822, for example). The S trace method is a method for measuring the amount of sulfur content per unit time contained in the exhaust gas from the engine to calculate the amount of engine oil per unit time consumed with the fuel. 
     Normally, sulfur content in the engine oil is included in the exhaust gas as various compounds such as sulfur dioxide (SO 2 ), sulfur monoxide (SO), or hydrogen sulfide (H 2 S). 
     Therefore, in the S trace method, a typical light of sulfur needs to be measured optically to obtain the amount of sulfur compounds in the exhaust gas as a sulfur dioxide density. 
     Therefore, in order to perform the S trace method, a device for making the sulfur content in the exhaust gas to emit light and a device for optically measuring the emitted light are necessary. These devices are large in size, complicated to control, and expensive. 
     SUMMARY OF THE INVENTION 
     In order to overcome the problems described above, preferred embodiments of the present invention provide an engine oil measurement device that is small in size and able to measure engine oil consumption easily. 
     An engine oil consumption measurement device according to a preferred embodiment of the present invention measures the engine oil consumption of an engine lubricated by engine oil. The engine oil consumption measurement device preferably includes a sensing pipe housing, an exhaust gas introduction passage, and a flow amount measurement device. A sulfur dioxide sensing pipe arranged to sense sulfur dioxide is disposed in the sensing pipe housing. An exhaust gas introduction passage connects the engine and a first end of the sulfur dioxide sensing pipe. The exhaust gas introduction passage introduces exhaust gas from the engine to the sulfur dioxide sensing pipe. The flow amount measurement device measures the flow amount of the exhaust gas flowing in the sulfur dioxide sensing pipe. 
     An engine oil consumption measurement method according to a preferred embodiment of the present invention measures the engine oil consumption of the engine lubricated by engine oil. The engine oil consumption measurement method preferably includes a measurement step and a calculation step. The measurement step measures the density of the sulfur dioxide in the exhaust gas from the engine by using the sulfur dioxide sensing pipe arranged to sense the sulfur dioxide. The calculating process calculates the engine oil consumption of the engine based on the measured density of the sulfur dioxide. 
     The various preferred embodiments of the present invention provide an engine oil measurement device that is small in size and able to measure the engine oil consumption easily. 
     Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a measurement device according to a first preferred embodiment of the present invention. 
         FIG. 2  is a front view of an unused sensing pipe. 
         FIG. 3  is a front view showing a state of the sensing pipe after use. 
         FIG. 4  is a flow chart showing engine oil consumption measurement according to the first preferred embodiment of the present invention. 
         FIG. 5  is a flow chart showing engine oil consumption measurement according to a second preferred embodiment of the present invention. 
         FIG. 6  is a schematic view showing a measurement device according to a third preferred embodiment of the present invention. 
         FIG. 7  is a flow chart showing an engine oil consumption measurement according to the third preferred embodiment of the present invention. 
         FIG. 8  is a schematic view showing a measurement device according to a fourth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Preferred Embodiment 
     Structure of the Measurement Device 
     With reference to  FIG. 1 , an engine oil consumption measurement device  1  will be described. Although an engine  2  is illustrated as a separate unit in  FIG. 1 , the engine  2  may be mounted in a vehicle, for example, a motorcycle. Alternatively, the engine  2  may be mounted in a stationary system. 
     The engine  2  may use any type of fuel. However, fuel with a relatively low sulfur content, such as gasoline, for example, is preferable. 
     The measurement device  1  preferably includes a sensing pipe housing  21 , an exhaust gas introduction passage  3 , and a pump unit  27  including an integrated flow meter  30  as a flow amount measurement device. The sulfur dioxide sensing pipe  22  arranged to sense the sulfur dioxide (SO 2 ) is preferably disposed in the sensing pipe housing  21 . Each component of the measurement device  1  will be described in further detail with reference to  FIG. 1 . 
     The exhaust gas introduction passage  3  introduces the exhaust gas from the engine  2  to the sulfur dioxide sensing pipe  22  disposed in the sensing pipe housing  21 . The exhaust gas introduction passage  3  preferably includes a pipe  10 , a filter  11 , a pipe  12 , a flow amount change regulation mechanism  13 , a pipe  17 , a sub-chamber  18 , a pipe  19 , and a restrictor mechanism  20 . 
     A first end of the pipe  10  is connected to the engine  2 . In  FIG. 1 , an example in which the pipe  10  is directly connected to the engine  2  is illustrated. However, in a case that a muffler or the like is provided on the engine  2 , the pipe  10  may be connected to the end of the muffler. In other words, the pipe  10  may be directly connected to the engine  2 , or indirectly connected to the engine  2  through a muffler or the like. 
     The other end of the pipe  10  is connected to the pipe  12  through a filter  11 . Soot or the like contained in the exhaust gas of the engine  2  is removed by this filter  11 . Thereby, adhesion or deposition of the soot or the like downstream of the filter  11  is prevented. The filter  11  is preferably removable from the pipe  10  and  12 . Therefore, the filter  11  can be exchanged easily. A chamber  15 , which will be described below, or each pipe or restrictor mechanism can be also easily exchanged. The filter  11  is not limited to a specific type, and may be any filter generally used for exhaust gas. 
     Also, the filter  11  may absorb an interference gas for sensing sulfur dioxide in the sulfur dioxide sensing pipe  22 . For example, the filter  11  may react with the interference gas, and prevent the interference gas from reaching the sulfur dioxide sensing pipe  22 . Also, the filter  11  may adsorb the interference gas, and prevent the interference gas from reaching the sulfur dioxide sensing pipe  22 . 
     The pipes  10  and  12  are not limited specifically. The pipes  10  and  12  are preferably made of materials having high thermal conductivity, for example. For example, the pipes  10  and  12  are preferably made of metal. Particularly, the pipes  10  and  12  are preferably made of copper. In the first preferred embodiment, a description is made for an example in which the pipes  10  and  12  are made of copper. 
     The flow amount change regulation mechanism  13  is attached to the pipe  12 . The flow amount change regulation mechanism  13  is a so-called rectification mechanism. Specifically, the flow amount change regulation mechanism  13  regulates the flow amount change of the exhaust gas. More specifically, the flow amount change regulation mechanism  13  regulates the pulsating flow of the exhaust gas, and brings the exhaust gas flow close to a rectified flow. In the first preferred embodiment, description is made for an example in which the flow amount change regulation mechanism  13  is defined by a restrictor mechanism  14  preferably disposed in the midsection of the pipe  12  and a chamber  15  attached to the end of the pipe  12 . In more detail, the chamber  15  is preferably a transparent chamber so that its inside can be observed. A pressure gage  16  arranged to measure pressure in the chamber  15  is disposed in the chamber  15 . 
     However, the flow amount change regulation mechanism  13  is not limited to the structure described above. The flow amount change regulation mechanism  13  may be defined by the restrictor mechanism  14  only, for example. Also, the flow amount change regulation mechanism  13  may be defined by the chamber  15  only. The flow amount change regulation mechanism  13  may be defined by a laminar flow forming device or a capillary device, for example. 
     The pipe  17  is connected to the chamber  15 . The sub-chamber  18  is connected to the end of the pipe  17 , and the exhaust gas from the chamber  15  is introduced into the sub-chamber  18 . The pipe  19  for supplying the exhaust gas to the sulfur dioxide sensing pipe  22  in the sensing pipe housing  21  is connected to the sub-chamber  18 . The end section of the sulfur dioxide sensing pipe  22  can be connected to the end section of the pipe  19 . Specifically, the end section of the pipe  19  is defined by, for example, a flexible tube such as a silicon tube. 
     The restrictor mechanism  20  is preferably disposed in the midsection of the pipe  19 . The exhaust gas supplied to the sulfur dioxide sensing pipe  22  is regulated by closing the restrictor mechanism  20 . On the other hand, the exhaust gas is supplied to the sulfur dioxide sensing pipe  22  by opening the restrictor mechanism  20 . Also, adjustment of the flow path area of the pipe  19  by the restrictor mechanism  20  regulates the flow amount of the exhaust gas supplied to the sulfur dioxide sensing pipe  22 . 
     In the first preferred embodiment, the sensing pipe housing  21  is preferably defined by a pair of contact plates  21   a  and  21   b  arranged so that they are facing each other. The sulfur dioxide sensing pipe  22  is fixed by being sandwiched between the contact plates  21   a  and  21   b . However, the sensing pipe housing  21  is not limited to a certain type as long as it can hold the sulfur dioxide sensing pipe  22 . 
     An exhaust gas discharge path  4 , for discharging the exhaust gas from the sulfur dioxide sensing pipe  22  disposed in the sensing pipe housing  21 , is disposed in the measurement device  1 . The exhaust gas discharge path  4  preferably includes a pipe  24 , the pump unit  27 , a pipe  31 , and an exhaust pipe  25 . The pipe  24  is connected to a second end of the sulfur dioxide sensing pipe  22  disposed in the sensing pipe housing  21 . The ends of the sulfur dioxide sensing pipe  22  can be connected to the end section of the pipe  24 , as well as the end section of the pipe  19 . Specifically, the end section of the pipe  24  is defined by, for example, a flexible tube such as a silicon tube. 
     A restrictor mechanism  23  is preferably disposed in the midsection of the pipe  24 . The exhaust gas supplied to the sulfur dioxide sensing pipe  22  is regulated by closing the restrictor mechanism  23 . On the other hand, the exhaust gas is supplied to the sulfur dioxide sensing pipe  22  by opening the restrictor mechanism  23 . Also, the adjustment of the flow path area of the pipe  24  by the restrictor mechanism  23  regulates the flow amount of the exhaust gas supplied to the sulfur dioxide sensing pipe  22 . That is, in the first preferred embodiment, the flow amount of the exhaust gas supplied to the sulfur dioxide sensing pipe  22  is regulated by the restrictor mechanisms  20  and  23 . 
     The back end of the pipe  24  is connected to the pump unit  27 . The pump unit  27  includes the integrated flow meter  30 , a pump  28 , and a restrictor mechanism  29 . The integrated flow meter  30  is connected to the pipe  24 . The integrated flow meter  30  calculates the flow amount of the exhaust gas flowing in the pipe  24 . The pump  28  is preferably connected to the downstream end of the integrated flow meter  30 . The restrictor mechanism  29  is connected to the downstream end of the pump  28 . The pipe  31  is connected to the restrictor mechanism  29 . The pipe  31  is connected to the exhaust pipe  25  extending from the sub-chamber  18 . The exhaust gas introduced into the measurement device  1  is discharged from the exhaust pipe  25  to the outside of the measurement device  1 . A restrictor mechanism  26  is preferably disposed in the midsection of the exhaust pipe  25 . The amount of the exhaust gas flowing in the exhaust pipe  25  can be regulated by the restrictor mechanism  26 . 
     Sulfur Dioxide Sensing Pipe 
       FIG. 2  is a plan view of an unused sulfur dioxide sensing pipe  22 . As shown in  FIG. 2 , the sulfur dioxide sensing pipe  22  is preferably an ampule having both ends welded. A sensing agent  22   f  is enclosed between enclosing members  22   d  and  22   e  in the sulfur dioxide sensing pipe  22 . When the sensing agent  22   f  comes into contact with a target gas (e.g., sulfur dioxide), the sensing agent  22   f  reacts and discolors. A scale  22   g  is printed on a section where the sensing agent  22   f  is enclosed. 
     When the sulfur dioxide sensing pipe  22  is used, first, weld enclosure sections  22   c  at both ends are cut off using a glass cutter or the like. After that, gas is introduced from a gas inlet  22   a . The enclosed sensing agent  22   f  is discolored if the introduced gas contains sulfur dioxide. The discoloration of the sensing agent  22   f  starts from the gas inlet  22   a  side. If the amount of sulfur dioxide in the gas introduced in the sulfur dioxide sensing pipe  22  is small, the sensing agent  22   f  in the vicinity of the gas inlet  22   a  is discolored. Discoloration of the sensing agent  22   f  proceeds toward the vicinity of a gas outlet  22   b  as the amount of sulfur dioxide in the gas introduced in the sulfur dioxide sensing pipe  22  increases. 
     In general, an amount of gas to be introduced to the sensing pipe at the time of measurement is defined in advance. For example, for the sulfur dioxide sensing pipe  22  shown in  FIG. 2 , the amount of gas introduced at the time of measurement is about 100 ml. The amount of gas introduced to the sulfur dioxide sensing pipe  22 , and the length of the discolored sensing agent  22   f  is measured by visual evaluation using the scale  22   g  printed on the sulfur dioxide sensing pipe  22 . In this way, the amount of sulfur dioxide in the gas introduced in the sulfur dioxide sensing pipe  22  is determined. For example, in a case that about 100 ml of gas is introduced to the sulfur dioxide sensing pipe  22  shown in  FIG. 2  and  FIG. 3 , if the discolored sensing agent  22   f   1  reaches the point where the scale 1.8 is printed as shown in  FIG. 3 , the sulfur dioxide contained in the introduced gas is determined to be 1.8 ppm. 
     The sensing agent  22   f  is preferably discolored only by the gas to be detected. However, the sensing agent  22   f  is not always discolored only by the gas to be detected. For example, the sensing agent  22   f  may be discolored by a gas other than the gas (sulfur dioxide) intended to be detected. The gas, which is not targeted for detection and discolors the sensing agent  22   f , is called an interference gas. If the sensing agent  22   f  will discolor when exposed to interference gas, the measurement is preferably performed in an environment free from the interference gas as much as possible. 
     The kind of sensing agent  22   f  is not specifically limited. The sensing agent  22   f  may have a starch-iodide reaction as a basic reaction principle. The sensing agent  22   f  may have, for example, a reduction reaction of potassium iodide, a reaction with alkali, or a reduction reaction of the dichromate as a basic reaction principle. Among these, the sensing agent  22   f  preferably has a starch-iodide reaction as a basic reaction principle. Specifically, it is preferable to have the following reaction equation (2) as a basic reaction principle. Hereinafter, description is made of an example in which the sensing agent  22   f  has the following equation (2) as a basic reaction principle:
 
SO 2 +I 2 (violet)+2H 2 O→2HI(white)+H 2 SO 4   (2)
 
     In the sensing agent  22   f  having the above reaction equation (2) as a basic reaction principle, iodine having a violet color due to the starch is reduced by sulfur dioxide, and becomes hydrogen iodide having a white color. Accordingly, the sensing agent  22   f  changes color from violet to white. The sensing agent  22   f  having the above reaction equation (2) as a basic reaction principle changes color from violet to brown when exposed to nitrogen dioxide. This is because nitrogen dioxide causes iodine having a violet color due to starch to separate from the starch and then change to brown. On the other hand, nitric oxide does not cause separation of iodine from starch. Therefore, the sensing agent  22   f  having the above reaction equation (2) as a basic reaction principle is not discolored by nitric oxide. That is, the sensing agent  22   f  having the above reaction equation (2) as a basic reaction principle includes nitrogen dioxide as an interference gas, but does not include nitric oxide as an interference gas. 
     Measurement Method of the Engine Oil Consumption Using the Measurement Device 
     Next, description is made for a measurement method of the engine oil consumption using the measurement device  1 , with reference mainly to  FIG. 4 . 
     As shown in  FIG. 4 , preparation of the engine  2  is performed first in step S 1 . If the engine  2  is mounted on a vehicle, preparation of a vehicle and positioning of a driver are also performed in step S 1  at the same time. 
     Next, preparation of the measurement device  1  is performed in step S 2 . Specifically, connection between the measurement device  1  and the engine  2 , preparation and arrangement of the sulfur dioxide sensing pipe  22 , pressure regulation in the measurement device  1  by the control of the restrictor mechanisms  14 ,  26  or the like, flow amount regulation by the control of the restrictor mechanism  14 , measurement of the sulfur component density in the engine oil to be measured, setting of the suction air amount to the measurement device  1 , and setting of the suction amount to the sulfur dioxide sensing pipe  22  or the like, are performed. Regulation of the flow amount change of the exhaust gas can be performed by the control of the restrictor mechanism  14 , so that the pressure gage attached to the chamber  15  reads low. The suction air amount may be performed by the actual measurement at the engine rotational speed to be measured. Also, in a case that the engine  2  has a suction air amount sensor, the suction air amount may be detected by monitoring the suction air amount sensor when necessary. 
     Steps S 1  and S 2  may be performed concurrently. Also, step S 2  may be performed in advance, and step S 1  may be performed after completion of step S 2 . That is, the order of step S 1  and step S 2  is not limited. 
     Next, in step S 3 , the engine  2  is driven and measurement of the engine oil consumption is performed. Specifically, in a state that engine  2  is driven at the predetermined rotational speed, the pump  28  is driven, and at the same time the restrictor mechanisms  20 ,  23 , and  29  are opened to start introduction of the exhaust gas into the sulfur dioxide sensing pipe  22 . The total amount of the exhaust gas sucked into the sulfur dioxide sensing pipe  22  is monitored by the flow amount measurement device  30 . According to the flow amount measurement device  30 , when the flow amount of exhaust gas in the sulfur dioxide sensing pipe  22  has reached the predetermined suction amount in reference to the sulfur dioxide sensing pipe  22 , step S 3  is finished by closing the restrictor mechanism  20  or the like. 
     The rotational speed of the engine  2  in step S 3  is not specified. However, if the sensing agent  22   f  has nitrogen dioxide as an interference gas, and the starch-iodide reaction is the basic reaction principle for example, the rotational speed of the engine  2  in step s 3  is preferably substantially the maximum rotational speed. In other words, it is preferable to perform step S 3  in a state that the engine  2  is driven substantially at the maximum speed. 
     Next, in step S 4 , the engine oil consumption is calculated based on the measurement result in step S 3 . Specifically, at first, the sulfur dioxide sensing pipe  22  is removed from the measurement device  1 . Density of the measured sulfur dioxide is obtained by observing the removed sulfur dioxide sensing pipe  22  by visual evaluation. Next, engine oil consumption (LOC) of the engine  2  is calculated, based on the following equation (3), according to the obtained density of the sulfur dioxide.
 
 LOC=[C ×(32.06/22.4)×{273/(273 +T   1 )}× Q]× 10 −4   /S   (3)
 
In which,
 
     LOC: engine oil consumption (g/h), 
     C: sulfur dioxide density (ppm) measured, 
     T: measurement temperature (° C.), 
     Q: amount of exhaust gas sucked into the sulfur dioxide sensing pipe  22  (L/h), and 
     S: density of the sulfur content in the engine oil (wt %). 
     For example, if 
     C=1.25 ppm, 
     Q=31680 (L/h), 
     T 1 =20° C., and 
     S=0.73 wt %, 
     engine oil consumption (LOC) is calculated as 7.234 g/h, according to the above equation (3). 
     Here, in a case that engine  2  is mounted, for example, on a motorcycle in which, 
     vehicle speed (s): 80 km/h, and 
     relative density of oil (γ) at temperature T 1 : 0.8775, 
     according to this condition, the conversion can be made as:
 
 LOC= 7.234g/h=( s ×γ)/7.234×1000≈9704km/L
 
     That is, in the case above, if the engine  2  is driven at the rotational speed of step S 3 , approximately 7.234 g of engine oil is calculated to be consumed every hour. Also, if the rotational speed of the engine  2  is fixed at the rotational speed of step S 3 , and if the motorcycle is driven 9704 km at 80 km/h, approximately one liter (L) of engine oil is calculated to be consumed. 
     Actions and Effects 
     As described above, according to the measurement device  1  using the sulfur dioxide sensing pipe  22 , the engine oil consumption is easily measured by using the sulfur dioxide sensing pipe  22 . Especially, with the measurement device  1 , rather complicated preparation work for measuring, such as gas correction before measuring required with a conventional S-trace device, is unnecessary. In the measurement device  1 , the measurement of the engine oil consumption can be started immediately, by only performing an easy measurement preparation work that regulates the flow amount of the exhaust gas. 
     Also, in the measurement device  1 , the engine oil consumption is measured by using the sulfur content in the engine oil. Therefore, in a case that the engine oil consumption is measured by using the measurement device  1 , unlike the gravimetric method or withdrawal method, it is not affected by dilution of the engine oil with water or gasoline. Thus, the engine oil consumption can be measured relatively accurately by using the measurement device  1 . 
     Furthermore, in the measurement device  1 , unlike the gravimetric method or withdrawal method, a relatively long measurement time such as a few hours to tens of hours is not necessary. In the measurement device  1 , by suction of the predetermined exhaust gas into the sulfur dioxide sensing pipe  22 , for example, the engine oil consumption measurement can be performed during relatively a short period of time such as a few minutes to tens of minutes. 
     The measurement device  1  has few elements and is compact in size compared to the conventional S-trace device. Specifically, the size of the measurement device  1  can be, for example, less than about one square meter. Therefore, transportation which would be difficult for the conventional S-trace device is relatively easy for the measurement device  1 . By using the measurement device  1 , the engine oil consumption measurement in the working area where a stationary type engine is equipped can be performed relatively easily. Also, in a relatively small vehicle such as a motorcycle, the measurement device  1  can be mounted on the vehicle, and the measurement of the engine oil consumption can be performed while driving the vehicle. 
     Also, the measurement device  1  is less expensive compared to the conventional S-trace device. In the measurement device  1  for measuring the engine oil consumption, a gas supply method for supplying the measurement gas such as hydrogen gas is not necessary. Also, the sulfur dioxide sensing pipe  22  is relatively inexpensive. Therefore, by using the measurement device  1 , the amount of capital investment for the engine oil consumption measurement can be decreased. Also, the running cost of the engine oil consumption measurement can be decreased. 
     The exchange of chambers  15 ,  18  or restrictor mechanism  14  or the like can be made easily in the measurement device  1 . So, in a case that the elements of the measurement device  1  become dirty by the exhaust gas, exchange of the chamber  15  or the like can be made easily. That is, the measurement device  1  has superior maintainability. 
     In a case that the engine oil consumption is measured by using the measurement device  1 , it is important to measure accurately the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22 . This is because the engine oil consumption is calculated based on the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22 . Here, exhaust gas in the engine  2  usually has a pulsating flow. That is, the flow amount of the exhaust gas discharged from the engine  2  is not always constant. Therefore, it is sometimes difficult to measure accurately the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22  with the integrated flow meter  30  when the sulfur dioxide sensing pipe  22  is connected to the engine  2  directly. As a result, it is sometimes difficult to calculate the engine oil consumption accurately. 
     On the other hand, in the measurement device  1 , the flow amount change of the exhaust gas of a pulsating flow is regulated by the flow amount change regulation mechanism  13 . Therefore, the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22  can be measured relatively accurately. Therefore, according to measurement device  1 , calculation of the engine oil consumption can be performed relatively accurately. 
     To regulate the flow amount change efficiently, it is preferable for the flow amount change regulation mechanism  13  to be disposed upstream of the sulfur dioxide sensing pipe  22 . However, the location of the flow amount change regulation mechanism  13  is not limited specifically. For example, the flow amount change regulation mechanism  13  may be disposed downstream of the sulfur dioxide sensing pipe  22 . 
     The structure of the flow amount regulation mechanism  13  is not limited specifically, too. However, the flow amount change regulation mechanism  13  is preferably defined by the restrictor mechanism  14  and the chamber  15  in the first preferred embodiment. Accordingly, the flow amount change regulation mechanism  13  can have a reduced cost. Also, exchange of the flow amount change regulation mechanism  13  becomes easy, thereby improving maintainability. 
     Also, in the measurement device  1 , the pump  28  is disposed downstream of the sulfur dioxide sensing pipe  22 . In step S 3  of measuring the sulfur dioxide density, the exhaust gas flowing in the sulfur dioxide sensing pipe  22  is sucked by this pump  28 . Accordingly, the flow amount of the exhaust gas flowing in the sulfur dioxide sensing pipe  22  is more stabilized. As a result, the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22  can be measured relatively accurately. Therefore, according to measurement device  1 , calculation of the engine oil consumption can be performed more accurately. 
     The step S 3  for measuring sulfur dioxide in the exhaust gas is preferably performed in the state in which the engine  2  is driven at substantially the maximum speed. By doing so, the fuel amount in the gas mixture supplied to the engine  2  can be relatively large. Therefore, the oxygen density in the combustion chamber in the engine  2  can be relatively low. As a result, generation of nitrogen dioxide (NO 2 ), which is an interference gas for sensing sulfur dioxide with a starch-iodide reaction as a basic reaction principle, can be minimized. Accordingly, the measurement of the sulfur dioxide density in the exhaust gas can be performed more accurately. 
     In the first preferred embodiment, the pipes  10  and  12  are preferably made of relatively high thermally conductive materials. Specifically, the pipes  10  and  12  are preferably made of copper. Therefore, the exhaust gas from the engine  2  can be cooled efficiently by the pipes  10  and  12 . Accordingly, the moisture content in the exhaust gas can be minimized. Also, the condensed moisture is trapped by the chamber  15  so intrusion of the moisture into the sulfur dioxide sensing pipe  22  is minimized. Furthermore, in the first preferred embodiment, the chamber  15  is transparent so the condensed moisture can be checked. 
     Second Preferred Embodiment 
       FIG. 5  is a flow chart showing the engine oil consumption measurement according to a second preferred embodiment. Hereinafter, while mainly referring to  FIG. 5 , the measurement method of the engine oil consumption according to the second preferred embodiment is described. In the description of the second preferred embodiment,  FIG. 1  is referred in common with the first preferred embodiment. In addition, components having practically the same function as described in the first preferred embodiment are indicated by common reference numerals, and the description thereof is not repeated. 
     As shown in  FIG. 5 , in the second preferred embodiment, step S 2  is followed by step S 10 . Specifically, in step S 10 , preparation of a fuel mixture or the like, in which the engine oil of the engine  2  is mixed with the fuel supplied to the engine  2  in a predetermined ratio, is performed. Step S 10  may be performed at any time, as long as it is performed before step S 3 - 2  which will be described below. For example, step S 10  may be performed after step S 3 - 1  which will be described below. The mixture ratio of the engine oil in relation to the fuel mixture is not limited specifically. The mixture ratio of the engine oil to the fuel may be, for example, between about 0.01% to about 20%. 
     Step  10  is followed by step S 3 - 1 . In step S 3 - 1 , engine  2  is driven in a state in which normal fuel without being mixed with the engine oil is supplied, and then the sulfur dioxide density of the exhaust gas is measured. Measurement of the sulfur dioxide density in step S 3 - 1  is the same as the method described in the first preferred embodiment. 
     Next, in step S 3 - 2 , the engine  2  is driven in a state in which the fuel mixture produced in step S 10  is supplied to the engine  2 , and then the sulfur dioxide density of the exhaust gas is measured. Measurement of the sulfur dioxide density in step S 3 - 2  is also the same as the method described in the first preferred embodiment. 
     Next, in step S 11 , the engine oil consumption is calculated based on the sulfur dioxide density measured in step S 3 - 1  and the sulfur dioxide density measured in step S 3 - 2 . In more detail, in step S 11 , the engine oil consumption is calculated based on the following equation (1). The amount (G) of the fuel mixture used in step S 3 - 2  can be calculated from the fuel consumption per unit time that is measured in advance, for example.
 
{C 2 /(C 1 −C 2 )}·G·R  (1)
 
Where,
 
     LOC: engine oil consumption (g/h), 
     C 1 : density (ppm) of the sulfur dioxide measured in step S 3 - 2 , 
     C 2 : density (ppm) of the sulfur dioxide measured in step S 3 - 1 , 
     G: amount of the fuel mixture used in step S 3 - 2  (g/h), and 
     R: mixture rate of the engine oil in reference to the fuel mixture. 
     For example, if: 
     sulfur dioxide density (C 2 ) measured in step S 3 - 1 : 0.5 ppm, 
     sulfur dioxide density (C 1 ) measured in step S 3 - 2 : 1.5 ppm, 
     amount of the fuel mixture (G) used in step S 3 - 2 : 100 g/h, 
     mixture rate of the engine oil (R) in reference to the fuel mixture: 0.01 (=1%), 
     the engine oil consumption (LOC) is calculated as 0.5 g/h, according to above equation (1). 
     Actions and Effects 
     In the second preferred embodiment, a comparison measurement is performed between the driving of the engine  2  to which normal fuel is supplied and the driving of the engine  2  in which the fuel mixture is supplied. Therefore, the effect of disturbances to the engine oil consumption measurement is reduced. As a result, the engine oil consumption can be more accurately measured. 
     Also, in the second preferred embodiment, in advance of the measurement of the engine oil consumption, clarifying the sulfur component content or the like in the engine oil is not necessary. Therefore, according to the measurement method in the second preferred embodiment, even if the sulfur component content in the engine oil is not known, the engine oil consumption can be easily measured. 
     Third Preferred Embodiment 
     In the first preferred embodiment, a description is made for a measurement device  1  that includes only one sulfur dioxide sensing pipe  22 . However, preferred embodiments of the present invention are not limited to this. For example, the measurement device may include a plurality of sensing pipes. Specifically, the measurement device may include two to five sensing pipes, for example. In the third preferred embodiment, a description is made for a measurement device  1   a  that includes three sensing pipes with reference to  FIG. 6 . In the description of the third preferred embodiment, components having practically the same function as in the first preferred embodiment are indicated by common reference numerals, and the description thereof is not repeated. 
     As shown in  FIG. 6 , a sensing pipe housing  41  and a sensing pipe housing  61  are provided together with the sensing pipe housing  21  in the measurement device  1   a  according to the third preferred embodiment. Also, pipes  19   a ,  19   b , and  19   c  are connected to the sub-chamber  18 . The pipe  19   a  is connected to the sensing pipe in the sensing pipe housing  21 , the pipe  19   b  is connected to the sensing pipe in the sensing pipe housing  41 , and the pipe  19   c  is connected to the sensing pipe in the sensing pipe housing  61 . Moreover, pipes  24   a ,  24   b , and  24   c  connect the sensing pipe in the sensing pipe housing  21 , the sensing pipe in the housing  41 , and the sensing pipe in the sensing pipe housing  61  to the pump unit  27 . Restrictor mechanisms  20   a ,  20   b ,  20   c ,  23   a ,  23   b , and  23   c  are disposed in the respective pipes  19   a ,  19   b ,  19   c ,  24   a ,  24   b , and  24   c.    
     For example, in a case that the engine oil consumption measurement is performed in the same way as in the first preferred embodiment, in which the sulfur dioxide sensing pipe  22  is only in the sensing pipe housing  21 , the measurement of the sulfur dioxide density can be performed in a state that the restrictor mechanisms  20   b ,  20   c ,  23   b , and  23   c  are closed. In a case that the engine oil consumption measurement is performed with the sensing pipe in all the sensing pipe housings  21 ,  41 , and  61 , the measurement of the sulfur dioxide density can be performed in a state that the restrictor mechanisms  20   a ,  20   b ,  20   c ,  23   a ,  23   b , and  23   c  are all opened. 
     The sensing pipe housings  41 ,  61 , for example, may be provided with an interference gas sensing pipe  42  for sensing the interference gas of the sulfur dioxide together with the sulfur dioxide sensing pipe  22 . Specifically, in a case that the sulfur dioxide sensing pipe  22  has a starch-iodide reaction as a basic reaction principle, the sensing pipe housings  41 ,  61 , for example, may be provided with the interference gas sensing pipe  42  for sensing nitrogen dioxide. Hereinafter, in the third preferred embodiment, description is made of the sensing pipe housing  41  provided with the interference gas sensing pipe  42 . 
     Measurement Method of the Engine Oil Consumption Using the Measurement Device 
     Next, referring mainly to  FIG. 7 , a detailed description is made for a measurement method of the engine oil consumption according to the third preferred embodiment of the present invention. 
     At first, in the third preferred embodiment, same as in the first preferred embodiment, step S 1  and step S 2  are performed in which the preparation of the engine  2  and measurement device  1   a  is performed. 
     Next, in step S 20 , the measurement of the sulfur dioxide density and interference gas density are performed concurrently. Specifically, the sulfur dioxide sensing pipe  22  and the interference gas sensing pipe  42  are arranged, respectively, in the sensing pipe housing  21  and the sensing pipe housing  41  in a state that the restrictor mechanisms  20   a ,  20   b , and  20   c , and the restrictor mechanisms  23   a ,  23   b , and  23   c  are closed. After that, the restrictor mechanisms  20   a ,  20   b , and the restrictor mechanisms  23   a  and  23   b  are opened, and the exhaust gas is introduced in the sulfur dioxide sensing pipe  22  and the interference gas sensing pipe  42 . According to the reading of the integrated flow meter  30 , when the amount of exhaust gas flowing in the sulfur dioxide sensing pipe  22  and the interference gas sensing pipe  42  reach the predetermined amount in reference to the respective sensing pipes, step  20  is finished by closing the restrictor mechanisms  20   a ,  20   b  or the like. 
     At this time, the ratio between the flow amount of the exhaust gas in the sulfur dioxide sensing pipe  22  and the flow amount of the exhaust gas in the interference gas sensing pipe  42  is not limited specifically. For example, the ratio between the flow amount of the exhaust gas in the sulfur dioxide sensing pipe  22  and the flow amount of the exhaust gas in the interference gas sensing pipe  42  may be equal to the ratio between the suction gas amount predetermined in relation to the sulfur dioxide sensing pipe  22  and the suction gas amount predetermined in relation to the interference gas sensing pipe  42 . By doing so, an integrated flow amount of the exhaust gas flowing in each of the sulfur dioxide sensing pipe  22  and the interference gas sensing pipe  42  can be obtained with the integrated flow meter  30 . 
     In the third preferred embodiment, in a case that a plurality of sensing pipes are arranged for measuring at one time, the different flow amount integrated meters may be disposed in the respective sensing pipes. Also, in step S 20 , the measurement of the sulfur dioxide density and interference gas density can be performed sequentially. Specifically, for example, after the measurement of the sulfur dioxide density is performed by opening the restrictor mechanisms  20   a  and  23   a  only, the measurement of the interference gas density can be performed by closing the restrictor mechanisms  20   a  and  23   a , and then opening the restrictor mechanisms  20   b  and  23   b.    
     As shown in  FIG. 7 , step S 20  is followed by step S 21 . Specifically, in step S 21 , a determination is made whether or not the interference gas density sensed by the interference gas sensing pipe  42  in step S 20  is less than the predetermined density. In more detail, in step S 21 , a determination is made whether or not the interference gas density sensed by the interference gas sensing pipe  42  in step S 20  is less than the maximum density of the interference gas predetermined in relation to the sulfur dioxide sensing pipe  22 . In other words, a judgment is made whether or not the density of the interference gas contained in the exhaust gas is within a range in which the sulfur dioxide sensing pipe  22  can be used. 
     In step S 21 , in a case that the determination is made that the interference gas density sensed by the interference gas sensing pipe  42  in step S 20  is less than the maximum density of the interference gas predetermined in relation to the sulfur dioxide sensing pipe  22 , it is followed by step S 4 . In step S 4 , same as in the first preferred embodiment, the calculation of the engine oil consumption is performed. 
     On the other hand, in step S 21 , in a case that the determination is made that the interference gas density sensed by the interference gas sensing pipe  42  in step S 20  is more than the maximum density of the interference gas predetermined in relation to the sulfur dioxide sensing pipe  22 , it is not followed by step S 4  but the process is ended. That is, in this case, the calculation of the engine oil consumption is stopped. 
     As shown in  FIG. 7 , step S 4  is followed by step S 22 . Specifically, in step S 22 , the correction of the engine oil consumption calculated in step S 4  is performed based on the interference gas density measured in step S 20 . This correction is performed based on the correlation between the predetermined interference gas density and a correction value. In this way, the calculation of the engine oil consumption in consideration of the interference gas density can be performed. 
     The correlation between the interference gas density and the correction value can be defined, for example, by performing experiments beforehand, in which the gas mixture intentionally made with a predetermined mixture ratio between the interference gas and the gas to be sensed is passed into the sulfur dioxide sensing pipe  22 . 
     Actions and Effects 
     A plurality of sensing pipe housings  21 ,  41 ,  61  are disposed in the measurement device  1   a  according to the third preferred embodiment. Therefore, measurement can be performed by providing a plurality of sensing pipes in the measurement device  1   a  at once. Thus, the densities of a plurality of types of gas can be measured at once, as necessary. As a result, according to the measurement device  1   a , the measurement of the exhaust gas for other contents can be performed together with the calculation of the engine oil consumption. For example, according to the measurement device  1   a , the measurement of the interference gas density can be performed together with the measurement of the sulfur dioxide density. 
     Also, for example, the measurement of the sulfur dioxide density can be performed while a plurality of sulfur dioxide sensing pipes  22  are provided. By doing so, accuracy of the calculation of the engine oil consumption can be improved. 
     In the measurement of the engine oil consumption according to the third preferred embodiment, in step S 22 , the engine oil consumption calculated in step S 4  is corrected based on the interference gas density measured in step S 20 . Therefore, a decrease of the measurement accuracy of the engine oil consumption based on the interference gas can be minimized. In other words, the engine oil consumption can be measured more accurately. 
     Also, in step S 21 , in a case that the interference gas density contained in the exhaust gas is determined to be higher than the predetermined density, the calculation of the engine oil consumption is stopped. Therefore, reliability of the calculated engine oil consumption can be improved. According to the third preferred embodiment, in step S 21 , the calculation of the engine oil consumption is performed in a case that the interference gas density contained in the exhaust gas is less than the predetermined density. However, in a case that more accurate engine oil consumption is necessary, the calculation of the engine oil consumption may be stopped when the interference gas is sensed in step S 20 . 
     Fourth Preferred Embodiment 
     According to the first to third preferred embodiments, a description is made for an example in which the operator of the measurement device calculates the engine oil consumption manually, or by using a separate calculation device from the measurement device. However, the preferred embodiments of the present invention are not limited thereto. For example, the measurement device may include a calculation unit to calculate the engine oil consumption. In the fourth preferred embodiment, a description is made for an example shown in  FIG. 8  in which the measurement device  1   b  includes a calculation unit  50 . In the description of the fourth preferred embodiment,  FIG. 7  is referred in common with the third preferred embodiment. Also, in the description of the fourth preferred embodiment, components having practically the same function as in the first and second preferred embodiments are indicated by common reference numerals, and the description thereof is not repeated. 
     As shown in  FIG. 8 , the measurement device  1   b  according to the fourth preferred embodiment includes the calculation unit  50 , a display  51 , an input unit  52 , and a drive unit  53 . The calculation unit  50  is connected to the integrated flow meter  30 , the display  51 , the input unit  52 , and the drive unit  53 . The input unit performs an input action of various data to the calculation unit  50 . The display  51  displays the input data and the calculation results or the like by the calculation unit  50 . The drive unit  53  opens and closes the restrictor mechanisms  20   a ,  20   b , and  20   c  respectively, based on commands from the calculation unit  50 . That is, according to the fourth preferred embodiment, the restrictor mechanisms  20   a ,  20   b , and  20   c  are opened or closed automatically by the drive unit  53 . 
     According to the fourth preferred embodiment, in step S 2 , the operator of the measurement device  1   b  inputs various settings to the calculation unit  50  using the input unit  52 . Specifically, the input data includes, for example, the measurement temperature (T 1 ) for the equation (3), the density of the sulfur content contained in the engine oil (S), the amount of the exhaust gas sucked in the sulfur dioxide sensing pipe  22  in step S 20  (Q), integrated flow amount of the exhaust gas sucked in the sulfur dioxide sensing pipe  22 , the correlation between the interference gas density and the correction value, or the like. 
     Next, in step S 20 , a restrictor mechanism release signal is outputted to the drive unit  53  by the calculation unit  50  with the operation of the input unit  52  by the operator of the measurement device  1   b . By doing this, the restrictor mechanisms  20   a  and  20   b  are opened, and the measurement of the sulfur dioxide density is started. In step S 20 , the calculation unit  50  monitors the integrated flow meter  30 . When the integrated flow meter  30  senses the integrated flow of the exhaust gas sucked in the sulfur dioxide sensing pipe  22 , the calculation unit  50  outputs the restrictor mechanism close signal to the drive unit  53 . Accordingly, the restrictor mechanisms  20   a  and  20   b  are closed, and the measurement of the sulfur dioxide density is finished. 
     After completion of step S 20 , the operator of the measurement device  1   b  obtains the sulfur dioxide density and the interference gas density in the exhaust gas by visually observing the sulfur dioxide sensing pipe  22  and the interference gas sensing pipe  42 . The operator inputs the obtained sulfur dioxide density and interference gas density to the calculation unit  50  with the input unit  52 . Accordingly, step S 21 , step S 4 , and step S 22  are performed automatically by the calculation unit  50 . Specifically, at first, in step S 21 , the calculation unit  50  determines whether or not the interference gas density in step S 20  is less than the predetermined density. If it is determined that the interference gas density is higher than the predetermined density in step S 20 , the display  51  shows NG, meaning that the engine oil consumption measurement cannot be performed, and step S 4  is stopped. On the other hand, in step S 21 , if it is determined that the interference gas density is less than the predetermined density in step S 20 , it is followed by step S 4 , and the engine oil consumption is calculated based on the equation (2) by the calculation unit  50 . Furthermore, in step S 22 , the engine oil consumption calculated in step S 4  is corrected by the calculation unit  50  based on the correlation between the predetermined interference gas density and the correction value. And, the corrected engine oil consumption is shown on the display  51 . 
     Other Preferred Embodiments 
     According to the first preferred embodiment, a description is made of an example in which the engine oil consumption measurement is performed preferably by using the sulfur dioxide sensing pipe  22  in step S 2  immediately after the preparation of the measurement device  1  is performed. However, preferred embodiments of the present invention are not limited thereto. For example, in step S 2 , a confirmation, in which the nitrogen dioxide density is less than the predetermined density by using the nitrogen dioxide sensing pipe for sensing the nitrogen dioxide, may be made after the preparation of the measurement device  1  is performed, and then the measurement of the engine oil consumption may be performed in step S 3 . 
     Although an engine  2  is illustrated as a separate unit in  FIG. 1 , the engine  2  may be mounted, for example, in a vehicle, such as a motorcycle. Also, the engine  2  may be mounted in a stationary device. Also, a pipe  10  is directly connected to the engine  2  in an example of  FIG. 1 . However, the pipe  10  may be connected to the end of a muffler if the muffler or the like is attached to the engine  2 . In other words, the pipe  10  may be indirectly connected to the engine  2  through the muffler or the like. 
     In the preferred embodiments above, description is made of an example in which a flow amount change regulation mechanism  13  is preferably defined by a restrictor mechanism  14  and a chamber  15 . The preferred embodiments of the present invention, however, are not limited to this. The flow amount change regulation mechanism  13  may be defined by, for example, the restrictor mechanism  14  only. Also, the flow amount change regulation mechanism  13  may be defined by the chamber  15  only. The flow amount chamber regulation mechanism  13  may be defined by, for example, a laminar flow forming device or a capillary device. 
     In the first preferred embodiment, a description is made of a measurement device  1  that preferably includes only one sulfur dioxide sensing pipe  22 . However, preferred embodiments of the present invention are not limited to this. For example, the measurement device can include a plurality of sensing pipes. Specifically, the measurement device may include two to five sensing pipes. Also, the sensing pipe housing  21  may be arranged such that a separate tubing from the sulfur dioxide sensing pipe  22  is arranged in series with the sulfur dioxide sensing pipe  22 . For example, the sensing pipe housing  21  may be arranged such that a pre-treatment pipe for decreasing the interference gas in the sulfur dioxide sensing pipe  22  by attachment or absorption is disposed upstream of the sulfur dioxide sensing pipe  22  and in series with the sulfur dioxide sensing pipe  22 . 
     In the third preferred embodiment, a description is made for an example in which the interference gas of the sulfur dioxide sensing pipe  22  is of one type, and only one interference gas sensing pipe  42  is provided. However, the quantity of the interference gas sensing pipe  42  is not limited specifically. For example, if there are a plurality of interference gases for sensing sulfur dioxide in the sulfur dioxide sensing pipe  22 , a plurality of interference gas sensing pipes  42  may be provided. 
     Definition of Terms in the Specification 
     In the preferred embodiments of the present invention, “interference gas” in the sensing pipe indicates a gas that interferes with the sensing of the gas to be sensed by the sensing pipe. In other words, “interference gas” is a gas whose existence makes the measurement value of the gas to be sensed by the sensing pipe to become inaccurate. As an interference gas, for example, there is a gas that reacts to the reagent of the sensing pipe and discolors the sensing pipe. “Interference gas” may be referred to by another name. 
     Preferred embodiments of the present invention are useful for engine oil consumption measurement. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.