A cylinder head countersink structure for preventing valve guide deformation in an engine

Abstract

The invention discloses a cylinder head countersink structure for preventing deformation of valve guide of an engine, comprising a cylinder head and a valve guide; the middle and lower part of the valve guide hole of the cylinder head is conical, and a countersink is provided on the upper part; a conical convex body is provided on the middle and lower part of the valve guide; the inner diameter of the countersink is 1 to 3 mm larger than the outer diameter of the upper part of the valve guide, and its depth accounts for 10% to 25% of the depth of the valve guide hole below the countersink. The invention has the beneficial effect of significantly improving the reliability and service life of the valve guide, and can significantly reduce the occurrence of banana deformation of the valve guide.

Description

Technical Field

[0001] The invention relates to the technical field of engine valve guides, and in particular to a cylinder head countersunk hole structure for preventing engine valve guides from deforming. Background Art

[0002] Compared with general diesel engines, the explosion pressure of National VI diesel engines is relatively high, and the temperature of the engine cylinder head will generally be high. In the case of insufficient cooling capacity of the cylinder head, the contact part of the cylinder head and the valve guide will deform unevenly due to uneven temperature distribution, resulting in a large difference in the gap between the cylinder head and the valve guide. The gap in some positions may be negative, exceeding the oil film protection range, and eventually causing the valve guide to deform like a banana. At the same time, it may also be based on the fact that the upper part of the traditional valve guide is exposed, resulting in heat dissipation and vibration coefficients that are different from the lower part, which increases the deformation difference.

[0003] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a cylinder head countersink structure with good reliability for preventing valve guide deformation of an engine.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A cylinder head countersink structure for preventing valve guide deformation of an engine comprises a cylinder head and a valve guide; the lower and middle parts of the valve guide hole of the cylinder head are conical, and a countersink is provided on the upper part; and a conical convex body is provided on the lower and middle parts of the valve guide.

[0007] Furthermore, the inner diameter of the counterbore is 1 to 3 mm larger than the outer diameter of the upper portion of the valve guide, and its depth accounts for 10% to 25% of the depth of the valve guide hole below the counterbore.

[0008] Furthermore, a sleeve spring slot is provided above the countersunk hole; a shock-absorbing spring and a barrier sleeve are distributed in the sleeve spring slot; a pressure cap threaded opening is provided on the top of the valve guide; the shock-absorbing spring is sleeved on the outside of the valve guide, and the barrier sleeve is sleeved on the outside of the shock-absorbing spring; an annular pressure cap is provided corresponding to the pressure cap threaded opening, and the shock-absorbing spring is compressed and fixed in the barrier sleeve through the annular pressure cap.

[0009] Furthermore, sealing gaskets are provided at the upper and lower ends of the barrier sleeve.

[0010] Furthermore, the conical convex body of the valve guide is narrow at the top and wide at the bottom.

[0011] Furthermore, the valve guide is interference fit with the cylinder head.

[0012] The beneficial effects of the present invention compared with the prior art are as follows: the present invention aims at the problem of banana-shaped deformation that is common in National VI diesel engines; a conical convex structure that is narrow at the top and wide at the bottom is provided in the middle and lower parts of the valve guide, while retaining the conventional pipe diameter structure of the lower part. In this way, the contact volume between the valve guide and the valve seat will not be increased, and the thickness and rigidity of the middle and lower parts of the valve guide will be improved. The conical shape is beneficial to increasing the thermal contact area between the key part and the cylinder head body. A countersunk hole design is added in combination with the cylinder head to reduce the length of the contact section between the valve guide and the cylinder head, thereby optimizing the cooling / heat dissipation problem of the upper, middle and lower layers of the valve guide, and effectively solving the problem of deformation caused by uneven temperature of each section. By providing a shock-absorbing spring, a barrier sleeve and an annular pressure cap, the upper end of the valve guide can be squeezed by the annular pressure cap to squeeze the shock-absorbing spring, thereby reducing the deviation of the vibration coefficient between the upper section of the valve guide and the cylinder head, thereby improving the stability and reliability of the valve guide. At the same time, the barrier sleeve can also effectively block the direct contact between the upper section of the valve guide and the outside of the cylinder head, effectively reducing the temperature difference between the upper section and the middle and lower sections of the valve guide, thereby improving the reliability of the entire valve guide. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the combined structure of the valve guide and the cylinder head of the present invention;

[0014] Figure 2 It is a schematic diagram of the structure of the present invention after assembly. DETAILED DESCRIPTION

[0015] like Figures 1-2As shown, a cylinder head counterbore structure for preventing valve guide deformation of an engine includes a cylinder head 1 and a valve guide 2; the middle and lower part of the valve guide hole 1-1 of the cylinder head 1 is conical, and a counterbore 1-2 is provided on the upper part thereof, and a valve seat cavity 1-4 is provided above the counterbore; the middle and lower part of the valve guide 2 is provided with a conical convex body 2-2 corresponding to the middle and lower part of the valve guide hole 1-1. The conical convex body 2-2 of the valve guide of this embodiment is narrow at the top and wide at the bottom, and of course the middle and lower part of the valve guide hole 1-1 is also opened in this way. This embodiment adopts this opening method mainly to combine the elasticity of the shock absorbing spring and the annular pressure cover of the present invention to improve the reliability of operation after assembly. The inner diameter of the counterbore 1-2 of this embodiment corresponds to the outer diameter of the upper part 2-3 of the valve guide 2, which is 1 to 3 mm larger. The selection of this outer diameter is based on the test data of the expansion degree of the commonly used materials of the valve guide and the cylinder head during the operation of the National VI engine, mainly to ensure that the outer wall of the valve guide does not contact the valve guide hole during the operation. The depth of the counterbore 1-2 accounts for 10% to 25% of the depth of the valve guide hole below the counterbore. Because the counterbore 1-2 is provided, the valve guide 2 also needs to be designed with a conical convex body 2-2 to ensure reliability. A sleeve spring slot 1-3 is also provided above the counterbore 1-2; a damping spring 4 and a blocking sleeve 7 are distributed in the sleeve spring slot 1-3; a gland threaded opening 2-4 is provided at the top of the valve guide 2; the damping spring 4 is sleeved on the outside of the valve guide 2, and the blocking sleeve 7 is sleeved on the outside of the damping spring 4; an annular gland 6 is also provided corresponding to the gland threaded opening, and the damping spring is compressed and fixed in the blocking sleeve through the annular gland 6, that is, the upper end of the valve guide 2 is connected to the cylinder head 1 through the damping spring, thereby improving its reliability. In order to improve the temperature stability in the blocking sleeve 7, sealing gaskets 3, 5 are also provided at the upper and lower ends of the blocking sleeve 7, aiming to improve the uniformity of the temperature of each section of the entire valve guide 2. Of course, the valve guide 2 and the cylinder head 1 are interference fit.

Claims

1. A cylinder head countersink structure for preventing valve guide deformation of an engine, characterized in that: It comprises a cylinder head and a valve guide; the lower and middle parts of the valve guide hole of the cylinder head are conical, and a countersunk hole is provided on the upper part; the lower and middle parts of the valve guide are provided with a conical convex body; The inner diameter of the counterbore is 1 to 3 mm larger than the outer diameter of the upper portion of the valve guide, and its depth accounts for 10% to 25% of the depth of the valve guide hole below the counterbore; A sleeve spring slot is also provided above the counterbore; a damping spring and a barrier sleeve are distributed in the sleeve spring slot; a gland threaded opening is provided at the top of the valve guide; the damping spring is sleeved on the outside of the valve guide, and the barrier sleeve is sleeved on the outside of the damping spring; an annular gland is also provided corresponding to the gland threaded opening, and the damping spring is compressed and fixed in the barrier sleeve through the annular gland; Sealing gaskets are also provided at the upper and lower ends of the barrier sleeve; The conical convex body of the valve guide is narrow at the top and wide at the bottom.

2. The cylinder head countersink structure for preventing valve guide deformation of an engine according to claim 1, characterized in that: The valve guide is interference fit with the cylinder head.

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