Patent Application
20090143000
1. Field of the Invention
The present disclosure is related to internal combustion engines. More particularly, the present disclosure is related to devices for finishing the surface of valve seats in such internal combustion engines.
2. Description of Related Art
Internal combustion engines include an intake valve assembly and an exhaust valve assembly. During operation of the engine, the valve assemblies allow air-fuel mixtures and combustion by-products to selectively enter and exit the combustion chamber of the engine in a known manner.
The valve assemblies include a poppet valve received in the cylinder head of the internal combustion engine. The poppet valve has a sealing face and a valve stem. The cylinder head includes a valve seat and a valve guide. The valve stem is slideably received in the valve guide so that the sealing face can selectively seal against and unseal from the valve seat.
In internal combustion engines, it is desired that the cylinders be airtight when the valve assemblies are closed to assure efficient fuel consumption and transfer of power. This airtightness is achieved by, among other things, assuring that the valve faces match the valve seats. Since the valve faces and valve seats are subject to wear and other degrading factors that affect the surface finish, the face and seat are often repaired to re-establish the quality of the seal.
In order to provide the desired tolerance between the valve face and the valve seat, a machining or cutting operation is typically performed. The machining or grinding operation removes the outer surface of the seat and face to expose a relatively smooth contact surface. Machining or grinding operations on the valve face are relatively straightforward due to the high mobility of the poppet valve.
However, machining and/or grinding operations on the valve seat are made difficult by the size and weight of the cylinder head. Currently, valve seat and guide machines are available for performing the machining and/or cutting operation of the cylinder head, which has greatly increased the ease with which the valve seat and valve guide can be refinished.
Unfortunately, the machining and/or grinding operation alone usually does not provide sufficient surface finish to the valve seat. Thus, after machining and/or grinding the valve seats, it is required that the valve seat be manually finished to the desired surface finish, which requires removal of the cylinder head from the machine and, thus, increases the cost and time associated with such repairs.
Moreover, the machine tools used in such machine operations require frequent re-sharpening, while the grinding tools used in such grinding operations require frequent re-dressing. Thus, the valve seat and guide machines, while adding precision to the process, can increase the time required to resurface the valve seat due to constant repair and dressing of the machine and grinding tools, respectively.
Accordingly, it has been determined by the present disclosure that there is a need for devices that finish the surfaces of valve seats while overcoming, alleviating, and/or mitigating one or more of the aforementioned and other deleterious effects of the prior art.
A valve seat finishing device for use with a spindle having a drive is provided. The valve seat finishing device includes a driver, a valve seat finishing tool, an annular finishing surface on the tool, and a non-dressable super abrasive on the annular finishing surface. The driver has a centering portion and a drive portion. The centering portion is received in a receiving portion of the drive and the drive portion is received in the drive so that rotation of the spindle causes the socket drive to concentrically rotate the driver. The valve seat finishing tool is threadably secured to the driver. The non-dressable super abrasive provides a lapped finish to the valve seat.
In some embodiments, the valve seat finishing device includes a ball driver and a valve seat finishing tool threadably secured to the ball driver. The ball driver has a centering surface and a drive pin. The centering surface is received in a receiving surface of the socket drive and the drive pin received in a drive pin slot of the socket drive so that rotation of the spindle causes the socket drive to concentrically rotate the ball driver. The valve seat finishing tool provides a lapped finish to the valve seat.
In other embodiments, the valve seat finishing device includes a cone driver and a valve seat finishing tool threadably secured to the cone driver. The cone driver has a cone-shaped surface and a key. The cone-shaped surface is received in a receiving surface of the tapered drive and the key is received in a keyway of the tapered drive so that rotation of the spindle causes the tapered drive to concentrically rotate the cone driver. The valve seat finishing tool provides a lapped finish to the valve seat.
A method of finishing a valve seat is also provided. The method includes operating a machine to rotate a spindle so as to machine and/or grind the valve seat; connecting a valve seat finishing tool to the spindle, the valve seat finishing tool having an annular finishing surface at a desired angle with a plated super abrasive thereon; and operating the machine to rotate the spindle so as to finish the valve seat to a lapped finish.
The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.
Referring to the drawings and in particular to
In such prior art machines 10, spindle 16 is configured to rotate a chuck or drive 26 having a machining or grinding tool (not shown) secured therein so as to machine or grind seats 12 and/or valve guides 24. Unfortunately, the ground surface finish and machined surface finish is typically not sufficient to provide a leak proof seal to valve seat 12.
Advantageously, the present disclosure provides a valve seat finishing device 30 shown in
In embodiments where drive 26 is a socket drive 32, device 30 includes a ball driver 34, a valve seat finishing tool 36, and a pilot shaft 38. In some embodiments, system 30 further includes a compression spring 40. For purposes of clarity, ball driver 34 and tool 36 are illustrated as cross sections.
Socket drive 32, ball driver 34, and pilot shaft 38 can be made of any material having sufficient hardness and heat resistance. In some embodiments, socket drive 32 and ball driver 34 are made of heat treated steel having a black oxide coating, while pilot shaft 38 is made of carbide or tool steel.
Socket drive 32 is configured for securement to spindle 16 of machine 10 so that rotation of the spindle about the x-axis 18 is imparted to the socket driver. For example, socket drive 32 can include a flattened end 42 drivingly received by spindle 16.
Socket drive 32 includes a receiving surface 44 and a drive pin slot 46 having an open bottom end 48. Ball driver 34 includes a centering surface 54 and a drive pin 56. In use, receiving surface 44 receives centering surface 54 so that ball driver 34 is centered within socket drive 32 and so that drive pin 56 is received in drive pin slot 46. In this manner, ball driver 34 is releasably and concentrically secured to socket drive 32 so that rotation of spindle 16 causes socket drive 32 to rotate ball driver 34 about the x-axis 18.
It should be recognized that device 30 is illustrated by way of example having receiving surface 44/drive pin slot 46 on socket drive 32 and centering surface 54/drive pin 56 on ball driver 34. Of course, it is contemplated by the present disclosure for ball driver 34 to include receiving surface 44/drive pin slot 46 and socket drive 32 to include centering surface 54/drive pin 56 or any combinations thereof.
Ball driver 34 includes a first threaded portion 50, which is threadably engaged with a second threaded portion 52 of tool 36. In addition, ball driver 34 includes a first bore 58, while tool 36 includes a second bore 60. Bores 58, 60 are configured for receipt of pilot shaft 38 therein so that the pilot shaft is concentric to ball driver 34 and tool 36.
In some embodiments, pilot shaft 38 can freely spin within bores 58, 60, which results in a so called “dead-pilot” shown in the embodiment of
Tool 36 includes an annular finishing surface 64 having a plated super abrasive 66 thereon. In an exemplary embodiment, tool 36 is made of mild tool steel. In another exemplary embodiment, plated super abrasive 66 that can be a nickel plated diamond layer, a plated cubic-boron-nitride (CBN) layer, and any combinations thereof. Plated super abrasive 66 has a grit of above about 150 grit, with between about 180 to about 320 grit being preferred, and about 240 grit being most preferred.
Advantageously, plated super abrasive 66 eliminates the need for dressing before use as is required when using grinding wheels and eliminates the need for sharpening before use as is required when using machining tools.
In the preferred embodiment, annular finishing surface 64 has an angle (θ) with respect to the x-axis 18, where the angle θ corresponds to a desired angle of valve seat 12.
In use, pilot shaft 38 is configured for receipt in a valve stem guide 24 of cylinder head 14 so that the pilot shaft rotates about the x-axis 18 and moves along the x-axis. Thus, pilot shaft 38 maintains device 30 concentrically aligned with valve seat 12 throughout the finishing process. Spring 40, when used, can assist in maintaining plated super abrasive 66 of tool 36 out of contact with seat 12 until device 30 is at a desired speed, at which time compression of spring 40 along the x-axis 18 results in plated super abrasive 66 contacting and finishing seat 12. In the illustrated embodiment, spring 40 rests on a bottom face 68 of tool 36.
As it is desired for tool 36 to provide a lapped finish to valve seat 12, it is contemplated by the present disclosure for the desired speed of tool 36 to be limited to between about 30 to about 150 revolutions per minute, with between about 40 to about 50 revolutions per minute being preferred. Further, it is contemplated by the present disclosure for the cutting force of tool 36 (e.g., the force with which tool 36 is applied to valve seat 12) to be limited to between about 0 to about 10 pounds, with between about 1 to about 5 pounds being preferred. In this manner, tool 36 provides a typical lapping process having low cutting speed and low cutting forces, providing for shallow penetration of fine abrasive grains without generating significant heat to limit thermal damage.
In the embodiment of valve seat finishing device 30 shown in
Referring now to
Device 130 includes a cone driver 134, tool 36, and pilot shaft 38. In some embodiments, system 130 further includes a compression spring 40. For purposes of clarity, cone driver 134 and tool 36 are illustrated as cross sections.
Tapered drive 132, cone driver 134, and pilot shaft 38 can be made of any material having sufficient hardness and heat resistance. In some embodiments, tapered drive 132 and cone driver 134 are made of heat treated steel having a black oxide coating, while pilot shaft 38 is made of carbide or tool steel.
Tapered drive 132 is configured for securement to spindle 16 of machine 10 so that rotation of the spindle about the x-axis 18 is imparted to the tapered driver.
Tapered drive 132 includes a receiving surface 144 and a keyway 146. Cone driver 134 includes a cone-shaped surface 154 and a key 156. In use, receiving surface 144 receives cone-shaped surface 154 so that cone driver 134 is centered within tapered drive 132 and so that key 156 is received in keyway 146. In this manner, cone driver 134 is releasably and concentrically secured to tapered drive 132 so that rotation of spindle 16 causes tapered drive 132 to rotate cone driver 134 about the x-axis 18. In some embodiments tapered drive 132 also includes a bottom cap 170 threadably received on a bottom end 148. In this manner, cone driver 134 is maintained in tapered drive 132 by cap 170. Since cone driver 134 and tool 36 are connected to spindle 16 by cap 170, the need for compression spring 40 can, in some instances, be eliminated.
In some embodiments, key 156 can be removably secured to cone driver 134 by one or more set screws 172. In this manner, key 156 can be removed from cone driver 134 and replaced with a new, undamaged key 156.
Cone driver 134 includes a first threaded portion 150, which is threadably engaged with a second threaded portion 52 of tool 36. In addition, cone driver 134 includes a first bore 158, tool 36 includes a second bore 60, and bottom cap 170 includes a third bore 174. Bores 158, 60, 174 are configured for receipt of pilot shaft 38 therein so that the pilot shaft is concentric to cone driver 134 and tool 36.
In some embodiments, pilot shaft 38 can freely spin within bores 158, 60, 174 which results in a so called “dead-pilot”. In other embodiments, cone driver 134 further includes one or more threaded set screw openings 162 so that the cone driver can be releasably secured to pilot shaft 38 by way of one or more set screws (not shown), which results in a so called “live pilot”.
In use, pilot shaft 38 is configured for receipt in valve stem guide 24 of cylinder head 14 so that the pilot shaft rotates about the x-axis 18 and moves along the x-axis. Thus, pilot shaft 38 maintains valve seat finishing device 130 concentrically aligned with valve seat 12 throughout the finishing process. Spring 40, when used, can assist in maintaining plated super abrasive 66 of tool 36 out of contact with seat 12 until valve seat finishing device 130 is at a desired speed, at which time movement of device 130 along the x-axis 18 results in compression of spring 40 so that plated super abrasive 66 contacting and finishing seat 12. In the illustrated embodiment, spring 40 rests on bottom face 68 of tool 36.
Advantageously, valve seat finishing devices 30 and 130 allow an operator to use machine 10 to use known methods to machine and grind valve seat 12, and then to quickly insert socket drive 32 or tapered drive 132 into the spindle 16. With valve seat finishing devices 30 and 130, the operator can provide a lapped finish to valve seat 12 using machine 10 such that no additional manual operations are required.
In use, an operator first mounts cylinder head 14 of an internal combustion engine in machine 10. Then, the operator uses machine 10 to machine and/or grind valve seat 12. In some embodiments, valve seat finishing devices 30, 130 are configured to receive a threaded grinding wheel (not shown) on threads 50, 150 in place of tool 36.
When using socket drive 32, the operator secures tool 36 to ball driver 34 via threads 50, 52. In addition, the operator inserts pilot shaft 38 through bores 58, 60 and secures the pilot shaft to ball driver 34 using set screws in set screw openings 62. However, when using tapered drive 132, the operator secures tool 36 to cone driver 134 via threads 150, 52. In addition, the operator inserts pilot shaft 38 through bores 158, 60, 174 and secures the pilot shaft to cone driver 134 using set screws in set screw openings 162.
After machining and/or grinding valve seat 12, the operator secures socket drive 32 or tapered drive 132 to machine 10, slides spring 40 over pilot shaft 38, and inserts the pilot shaft into valve stem guide 24. In this position, spring 40 prevents plated super abrasive 66 from contacting valve seat 12. The operator activates machine 10 so as to rotate spindle 16 and, thus tool 36 about x-axis 18. Once tool 36 attains a desired speed, the operator moves tool 36 along x-axis 18 and into contact with valve seat 12 so that plated super abrasive 66 finishes the valve seat to the desired lap finish.
In use, valve seat finishing tool 36 provides a super abrasive seat lap which can be used directly on machine 10 and, thus, eliminates the need to remove cylinder head 14 from machine 10 for further processing. In this manner, tool 36 reduces the time and cost of refinishing cylinder head 14.
It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.
While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.
