| High pressure fuel pump -> Monitor Keywords |
|
|
 
High pressure fuel pumpRelated Patent Categories: Pumps, Expansible Chamber Type, Pumping Member Position Controlled PortHigh pressure fuel pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060104843, High pressure fuel pump. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application is based on and incorporates herein by reference Japanese Patent Application No. 2004-331599 filed on Nov. 16, 2004 and Japanese Patent Application No. 2005-240970 filed on Aug. 23, 2005. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a high pressure fuel pump. [0004] 2. Description of Related Art [0005] There is known a high pressure fuel pump, which pressurizes fuel in a pressurizing chamber by a plunger (See Japanese Unexamined Patent Publication No. 2001-295730 corresponding to US Patent Application Publication No. 2003/0103853 A1 and Japanese Unexamined Patent Publication No. H08-68370 corresponding to U.S. Pat. No. 5,567,134). In such a high pressure fuel pump, fuel leakage occurs from a side of a housing, which defines the pressurizing chamber, to a side of a drive means, which drives the plunger, and lubricant oil leakage occurs from the side of the drive means to the side of the housing. Because of this, the high pressure fuel pump recited in each of Japanese Unexamined Patent Publication No. 2001-295730 and Japanese Unexamined Patent Publication No. H08-68370 has a sealing means, which is engaged with an outer peripheral surface of the plunger. In this way, the outer peripheral surface of the plunger is fluid-tightly engaged with an inner peripheral surface of the sealing means to reduce leakage of fuel and leakage of lubricant oil. Furthermore, a high pressure fuel pump recited in Japanese Unexamined Patent Publication No. H11-6475 includes a sealing means that is engaged with an inner peripheral surface of the housing, which is in slidable engagement with the outer peripheral surface of the plunger. In this way, the inner peripheral surface of the housing is fluid-tightly engaged with the sealing means to reduce leakage of fuel and leakage of lubricant oil. [0006] However, in recent years, a required delivery rate of the high pressure fuel pump is increasing. Because of this, a size of the plunger and a size of the cylinder, which receives the plunger, are increasing. Therefore, in the case of the techniques recited in the above Japanese Unexamined Patent Publications, it is required to newly design a sealing means to correspond with an increase in a diameter of the plunger and an increase in a diameter of the cylinder. Therefore, a product number of the sealing means and a product number of molding dies are disadvantageously increased, and a relatively large number of steps is disadvantageously required for evaluating performance of the newly designed sealing means. [0007] Furthermore, the sealing means is engaged with the outer peripheral surface of the plunger or with the inner peripheral surface of the cylinder. Thus, when the diameter of the plunger or the diameter of the cylinder is substantially increased, the entire length of the contact area of the sealing means is lengthened. Therefore, the fuel and the oil can be easily leaked from the contact area. It is conceivable to increase the engaging force for engaging between the sealing means and the plunger or the housing, which forms the cylinder. However, when the engaging force is increased, wearing of the sealing means may be induced by the engagement between the sealing means and the plunger or the housing. As a result, the durability and reliability of the sealing means is disadvantageously reduced. [0008] Furthermore, when the diameter of the plunger is increased, the weight of the plunger is accordingly increased. This causes an increase in inertia of the plunger at the time of reciprocal movement of the plunger. Therefore, the ability of the plunger to follow the movement of the drive means is disadvantageously reduced. In order to increase the ability of the plunger to follow the movement of the drive means, a weight of an urging member, which urges the plunger against the drive means, needs to be increased. As a result, the drive force for driving the plunger is disadvantageously increased, thereby causing a substantial increase in the size. SUMMARY OF THE INVENTION [0009] Accordingly, it is an objective of the present invention to provide a high pressure fuel pump, which alleviates or eliminates a need for a modification of a design of a sealing means engaged with a plunger even when a diameter of at least a portion of the plunger or a diameter of a cylinder changes. It is another objective of the present invention to provide a high pressure fuel pump, which has a relatively high sealing performance and a relatively high reliability. It is another objective of the present invention to provide a high pressure fuel pump, which limits a substantial increase in a size of the high pressure fuel pump. [0010] To achieve the objectives of the present invention, there is provided a high pressure fuel pump, which includes a housing, a plunger, a drive means and a sealing means. The housing forms a cylinder therein. The cylinder communicates with a fuel intake passage and a fuel delivery passage in the housing. The plunger is reciprocably, slidably supported in the cylinder and includes an axial end surface, a large diameter portion, a small diameter portion. The axial end surface of the plunger defines a pressurizing chamber in corporation with the housing, and the plunger pressurizes fuel in the pressurizing chamber. The large diameter portion has an outer peripheral surface, which is slidably engaged with an inner peripheral surface of the housing, which forms the cylinder. The small diameter portion has an outer diameter smaller than an outer diameter of the large diameter portion and is connected to an opposite axial end of the plunger, which is opposite from the pressurizing chamber and the large diameter portion. The drive means is for reciprocally driving the plunger. The drive means is arranged at the opposite axial end of the plunger, which is opposite from the pressurizing chamber. The sealing means has a sliding surface, which is fluid-tightly engaged with an outer peripheral surface of the small diameter portion. BRIEF DESCRIPTION OF THE DRAWINGS [0011] The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which: [0012] FIG. 1 is a cross sectional view of a high pressure fuel pump according to a first embodiment of the present invention; [0013] FIG. 2 is a cross sectional view of the high pressure fuel pump of the first embodiment of the present invention, showing a plunger in a top dead center; [0014] FIG. 3 is a cross sectional view of a high pressure fuel pump according to a second embodiment of the present invention; [0015] FIG. 4 is a cross sectional view of a high pressure fuel pump according to a third embodiment of the present invention; [0016] FIG. 5 is a cross sectional view of a high pressure fuel pump according to a fourth embodiment of the present invention; [0017] FIG. 6 is a cross sectional view of a high pressure fuel pump according to a fifth embodiment of the present invention; [0018] FIG. 7 is a cross sectional view of a high pressure fuel pump according to a sixth embodiment of the present invention; [0019] FIG. 8 is a cross sectional view of a high pressure fuel pump according to a seventh embodiment of the present invention; [0020] FIG. 9 is a cross sectional view of a high pressure fuel pump according to an eighth embodiment of the present invention; and Continue reading about High pressure fuel pump... Full patent description for High pressure fuel pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this High pressure fuel pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like High pressure fuel pump or other areas of interest. ### Previous Patent Application: Pump unit Next Patent Application: Multip-stage piston type compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the High pressure fuel pump patent info. IP-related news and info Results in 0.16973 seconds Other interesting Feshpatents.com categories: Qualcomm , Schering-Plough , Schlumberger , Seagate , Siemens , Texas Instruments , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
