Patent Application
20180045137
This application claims the priority to Chinese Patent Application No. 201510084881.4 titled “INTERNAL COMBUSTION ENGINE PISTON HAVING INTERNAL COOLING CAVITY STRUCTURE AND INTERNAL COMBUSTION ENGINE”, filed with the Chinese State Intellectual Property Office on Feb. 16, 2015, the entire disclosure of which is incorporated herein by reference.
The present application relates to the technical field of internal combustion engine manufacturing, and more particularly to an internal combustion engine piston having an internal cooling cavity structure and an internal combustion engine.
In recent years, more strengthened and more lightened engines generate more and more load to pistons due to increasing pressure and temperature in cylinders. Subsequently, the cooling function and the strength of the material of a piston are more and more important.
At present, the maximum peak cylinder pressure (Max. pcp) in a diesel engine cylinder has exceeded 25 MPa. Aluminum alloy material can no longer meet such a high load bearing requirement. Therefore, manufacturers began to use forged steel and cast iron materials, which have better effects. However, this kind of piston has the following disadvantages: although the forged steel material can withstand a high temperature load, and a high temperature environment will cause the property of lubricating oil to degrade significantly, which increases the friction loss between the piston and the cylinder, and also increases carbon deposition. Thus, it is necessary to provide a cooling cavity inside the piston for enhancing the cooling effect. The forged steel piston with the internal cooling cavity can better meet the requirements of high burst pressure, high temperature working environment.
The manufacturing process of the cooling cavity is the difficulty and key in the manufacturing process of the internal combustion engine piston. Whether the manufacturing process is reasonable can often effect the service life of the piston to a great extent. An internal combustion engine piston having a cooling cavity structure typically includes a piston body and a ring body connected to the piston body in a fitted manner, with the cooling cavity being formed between the ring body and the piston body. In a current internal combustion engine piston, the top of the ring body is connected to the piston body by welding, and an welding surface is a closed cylindrical surface along the axis of the piston. One end of the closed cylindrical surface extends to the top of the piston, and another end extends to the cooling cavity. For the piston with a head having a large thickness, this method is apt to cause a situation of not achieving full penetration weld. If the full penetration weld is ensured, the heat affected area of the head of the piston may be inevitably increased, which may cause bad influence on the deformation of the piston head.
Therefore, a technical issue to be presently addressed by the person skilled in the art is to ensure the welding quality of the ring body with the piston body without increasing the heat affected area of welding.
In view of the above, it is an aspect of the present application to provide an internal combustion engine piston having an internal cooling cavity structure, so as to ensure the quality of welding between a ring body and a piston body without increasing the heat affected area by welding.
Another aspect of the present application is to provide an internal combustion engine having the internal combustion engine piston.
In order to achieve the above objects, the following technical solution is provided according to the present application.
An internal combustion engine piston having a cooling cavity structure, includes a piston body and a ring body fitted with the piston body to form the cooling cavity structure. The ring body and the top of the piston body form a first fitting region, and the ring body and a top end of a skirt portion of the piston body form a second fitting region. The first fitting region includes:
Preferably, the second fitting region is a stepped lapping area.
Preferably, the stepped lapping area includes:
Preferably, the stepped lapping area includes:
Preferably, in the case that the second support protrusion abuts against the second lapping groove, a lapping gap is further presented between the bottom surface of the ring body and the top end of the skirt portion of the piston body.
Preferably, the material of the ring body and the piston body is 42CrMoA.
Preferably, the material of the ring body and the piston body is 38MnVS6.
The internal combustion engine according to the present application, includes a cylinder and a piston provided in the cylinder. The piston is the internal combustion engine piston having the internal cooling cavity structure according to any one of the above aspects.
As can be seen from the above technical solution, in the internal combustion engine piston disclosed in the present application, the ring body and the top of the piston body form a first fitting region. The first fitting region includes the body fitting portion arranged at the top of the piston body, and a ring body fitting portion arranged at the top of the ring body. The body fitting portion is provided with the body welding cylindrical surface extending downwards from the top of the piston body, and the first support protrusion in connection with the bottom end of the body welding cylindrical surface and extending in the radial direction of the piston. The ring body fitting portion includes a ring body welding cylindrical surface configured to be fitted with the body welding cylindrical surface and a first lapping groove configured for receiving the first support protrusion, and the body welding cylindrical surface and the ring body welding cylindrical surface are connected to each other by welding.
Compared with the conventional technology, in the internal combustion engine piston disclosed in the present application, the ring body welding cylindrical surface is fitted with the body welding cylinder surface, and the welding seam formed by the welding has one end extending to the top of the piston and another end extending to a position connected to the first support protrusion rather than extending into the cooling cavity. The connection between the ring body and the piston body is achieved by the combination of welding and lapping. In the case that the thickness of the head of the piston keeps the same, the welding seam in the present application is significantly shortened, such that the full penetration welding can be more easily achieved on the head of the piston, thereby achieving the purpose of effectively ensuring the welding quality of the head of the piston without increasing the heat affected area of the head of the piston.
For more clearly illustrating embodiments of the present application or the technical solutions in the conventional technology, drawings referred to describe the embodiments or the conventional technology will be briefly described hereinafter. Apparently, the drawings in the following description are only some examples of the present application, and for the person skilled in the art, other drawings may be obtained based on these drawings without any creative efforts.
One of the aspects of the present application is to provide an internal combustion engine piston having an internal cooling cavity structure, so as to ensure the quality of welding between a ring body and a piston body without increasing the heat affected area of welding.
Another aspect of the present application is to provide an internal combustion engine having the internal combustion engine piston.
The technical solutions in the embodiments of the present application will be described clearly and completely hereinafter in conjunction with the drawings in the embodiments of the present application. Apparently, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all of other embodiments, made by the person skilled in the art without any creative efforts, fall into the scope of the present application.
Referring to
In the internal combustion engine piston disclosed in the above embodiment, the ring body welding cylindrical surface is fitted with the body welding cylinder surface, and a welding seam formed by the welding has one end extending to the top of the piston and another end extending to a position connected to the first support protrusion, rather than extending into the cooling cavity c. The connection between the ring body 1 and the piston body 2 is achieved by the combination of welding and lapping. Compared with the conventional technology, in the case that the thickness of a head of the piston keeps the same, the welding seam in the present application is significantly shortened, such that the full penetration welding can be more easily achieved on the head of the piston, thereby effectively ensuring the welding quality of the piston head without increasing the heat affected area of the head of the piston.
Referring specifically to
It is to be noted that, in the embodiment according to the present application, there may be a gap fit or an interference fit between the first body fitting surface 2-1 and the first ring body mating surface 1-1, and when the gap fit is employed, the gap value is not greater than 0.05 mm, and when the interference fit is employed, the interference value is not greater than 0.1 mm. There may also be a gap fit or an interference fit between the third body fitting surface 2-3 and the third ring body fitting surface 1-3, and when the gap fit is employed, the gap value is not greater than 0.05 mm, and when the interference fit is employed, the interference value is not greater than 0.1 mm.
As shown in
The second fitting region may be a threaded connection area, a welding area, etc., so long as it ensures that the second fitting region has a high tightness, so that an upper half cavity a in the ring body 1 and a lower half cavity b in the piston body 2 can form an integral internal cooling cavity c. In the embodiment of the present application, the second fitting region is specifically a stepped lapping area, as shown in
In one embodiment, the lapping area includes, specifically, a second support protrusion and a second lapping groove. Specifically, the second support protrusion is arranged on a bottom surface of the ring body 1 and extends in an axial direction of the piston. The width of the second support protrusion in the radial direction of the piston is less than the wall thickness of the ring body 1, and an inner wall of the second support protrusion is flush with an inner wall of the ring body 1, as shown in
Referring specifically to
When the ring body 1 is assembled with the piston body 2, a lapping gap is presented between the fourth ring body fitting surface 1-4 and the fourth body fitting surface 2-4, and the lapping gap preferably ranges from 0.1 mm to 1 mm, so as to ensure a reliable contact between the second support protrusion and the second lapping groove. There may be a gap fit or an interference fit between the fifth ring body fitting surface 1-5 and the fifth body fitting surface 2-5, and when the gap fit is employed, the gap value is not greater than 0.1 mm, and when the interference fit is employed, the interference value is also not greater than 0.1 mm.
In the above embodiment, the fourth body fitting surface 2-4 and the fifth body fitting surface 2-5 form an outer position-limiting ring, and the second support protrusion is just disposed inside the outer position-limiting ring, as shown in
Of course, on the basis of the above-described embodiments, the person skilled in the art can also make a variety of evolutionary variations for the fitting mode of the lapping area. As shown in
When the ring body 1 is assembled with the piston body 2, a ring groove 12 is machined on the ring body 1, and an oil belt 25 is machined on the piston body 2, and a combustion chamber structure is machined in a piston top 24.
The internal combustion engine piston having the internal cooling cavity structure disclosed in the present application is a forged steel piston, and the material of the ring body 1 and the piston body 2 is 42CrMoA or 38MnVS6.
As can be seen from the above embodiments, the first fitting region of the internal combustion engine piston disclosed in the present application employs the mode of combination of welding and lapping, which effectively reduces the length of the welding seam at the top of the piston, and achieves the object of improving the welding quality without increasing the heat affected area. The second fitting region employs a fitting mode of directly lapping, which greatly simplifies the manufacturing method of the piston, and may have a significant effect in releasing the residual stress after the assembly of the ring body 1 and the piston body 2 as well as resisting the deformation of the piston land region.
An internal combustion engine is further disclosed in the present application, and the piston in the internal combustion engine is the internal combustion engine piston disclosed in any one of the above embodiments.
Since the internal combustion engine employs the internal combustion engine piston disclosed in the above embodiments, the internal combustion engine also has the above-described corresponding advantages of the internal combustion engine piston, which is not described in this application.
The above embodiments are described in a progressive manner. Each of the embodiments is mainly focused on describing its differences from other embodiments, and references may be made among these embodiments with respect to the same or similar portions among these embodiments.
The description of the embodiments disclosed herein enables the person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to the person skilled in the art, and the general principle herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments described herein, but should be in accordance with the widest scope consistent with the principle and novel features disclosed herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201510084881.4 | Feb 2015 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2015/075869 | 4/3/2015 | WO | 00 |
