Process for variable depth press fitting of cylinder head guide tubes for extended range engines

Abstract

The application discloses a process for variable-depth press-fitting of a cylinder cover guide pipe of a range-extending engine, and comprises the following steps: step one, according to the relative position of the guide pipe bottom hole and spring nest depth size, taking the exhaust side spring nest as a rough machining reference, rough machining of the guide pipe press-fitting depth is carried out; step two, after rough machining, the guide pipe is cleaned and transferred to an automatic or manual press-fitting machine for press-fitting; step three, after the guide pipe press-fitting is completed, the guide pipe bottom hole and spring nest reference and the guide pipe bottom hole outer wall are respectively machined to the final size, and the consistency of the press-fitting depth of the cylinder cover intake and exhaust side guide pipe of the range-extending engine is completed. By redefining the guide pipe reference spring nest depth related machining size and adjusting the rough and fine spring nest depth reference difference, the press-fitting and machining of more kinds of engine cylinder cover gas distribution structures can be realized. While ensuring machining precision, the application can reduce the changeover time and save the production line modification cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of advanced manufacturing of new energy vehicles, and relates to a guide pipe press fitting and processing method, in particular to a machining method for variable guide pipe press fitting depth of different valve distribution structures of a cylinder cover of a hybrid range extending engine. BACKGROUND

[0002] With the development of the current new energy vehicle industry, the demand for hybrid range extending engines is increasing. Due to the engine layout problem, especially the fact that the range extending engine is not directly connected with the transmission, most of the engine oil, water and gas path sensors are arranged on the cylinder cover, which leads to the fact that the valve distribution structure, especially the guide pipes on the two sides of the intake and exhaust, are mostly no longer symmetrically arranged. Due to the difference in the overall valve distribution structure, the guide pipe press fitting depth of the cylinder cover of different engine models is different. The guide pipe press fitting mostly uses a spring nest or the top surface of the cylinder cover as a support surface limit, and uses a hydraulic cylinder for press fitting, which can meet the cylinder cover guide pipe seat ring press fitting standard of a large batch of uniform cylinder covers. SUMMARY

[0003] In order to adapt to the difference in the depth of the intake and exhaust side guide pipes of the cylinder cover of the range extending engine, the application provides a variable depth process for the guide pipe press fitting of the cylinder cover of the range extending engine. By redefining the guide pipe reference spring nest depth related machining size and designing a tool that can split the guide pipe and spring nest finishing, the press fitting and machining of more types of engine cylinder cover valve distribution structures can be realized by adjusting the rough and fine spring nest depth reference difference. The application can reduce the changeover time and save the production line modification cost while ensuring the machining precision.

[0004] The purpose of the application is achieved by the following technical solutions:

[0005] A variable depth process for the guide pipe press fitting of the cylinder cover of the range extending engine, comprising the following steps:

[0006] Step one, guide pipe press fitting depth rough machining

[0007] According to the relative position of the guide pipe bottom hole and the spring nest depth size, the exhaust side spring nest is used as the rough machining reference to perform the guide pipe press fitting depth rough machining. Among them: the intake side spring nest is directly machined to the final size using a compound tool holder, and no finishing is required after press fitting; in order to ensure the consistency of the position of the press head, the size of the exhaust side spring nest is left with a machining allowance in the axial and depth directions before press fitting, and the final state is machined using a compound tool holder after press fitting; the guide pipe hole cutter is a traditional compound cutter, and the guide pipe hole cutter is a two-blade diamond reamer. The diameters of the reamers for machining the spring nests are different. The diameter of the exhaust side is larger, and the diameter of the intake side is smaller. The height of the blade is low, and there is a margin in the diameter and depth directions;

[0008] Step two, press fitting

[0009] After rough machining, the conduit is transferred to an automatic or manual press for press fitting;

[0010] Step three, conduit press fitting depth finishing

[0011] After the conduit press fitting, the conduit bottom hole and spring nest reference and the conduit bottom hole outer wall are machined to the final size, and the consistency of the press fitting depth of the intake and exhaust side conduit of the extended range engine cylinder cover is completed.

[0012] Compared with the prior art, the present application has the following advantages:

[0013] 1. The present application provides a method for changing the front and rear process reference machining and manufacturing the press head and press head limit in the case of automatic line rigid press fitting, which can reduce the cost of modification and re-purchasing equipment caused by engine cylinder cover model changes, and improve the small batch and multi-model production capacity of the cylinder cover production line.

[0014] 2. The extended range engine needs to provide power corresponding to different vehicle types of direct drive motor or hybrid motor, and needs to be compatible with different valve train structures on the same platform model. In order to be compatible with different valve train structures of hydraulic tappet and cup-shaped tappet, the valve guide needs to use different conduit press fitting depth and conduit diameter on the same press fitting equipment. The present application provides a new machining process on the traditional machining (machining center, automatic line special machine) production line, which uniformly uses the spring nest as the rough machining reference for different model cylinder covers, and the press fitting machine manufactures a variety of adaptive press heads, unifies the conduit to spring nest press fitting depth size, and uses machining center to process in the rear process, and ensures the machining precision through the coaxial measuring tool and processing program, and realizes the machining of different valve train structures and variable conduit press fitting depth of the extended range engine cylinder cover. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a comparison diagram of the intake and exhaust side conduit press fitting depth size;

[0016] Figure 2 It is the spring nest machining size before press fitting;

[0017] Figure 3 It is a press fitting diagram of the press fitting machine;

[0018] Figure 4 It is a structure diagram of the conduit spring nest finishing reference tool;

[0019] Figure 5 It is a tool machining method diagram;

[0020] Figure 6 It is a machining size step diagram;

[0021] Figure 7 It is a valve seat press head before improvement;

[0022] Figure 8 Improved valve seat pressure head. DETAILED DESCRIPTION

[0023] The technical solutions of the present application are further described below in conjunction with the drawings, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present application without departing from the spirit and scope of the technical solutions shall be covered in the protection scope of the present application.

[0024] As shown in the comparison chart of the depth dimensions of the intake and exhaust side conduits in Figure 1 It can be seen from the comparison chart of the depth dimensions of the intake and exhaust side conduits in

[0025] In order to meet the pressing of the size difference of 1.2 mm, the relative position of the depth dimensions of the conduit bottom hole and the spring nest can be adjusted by the rough machining program. The rough machining setting dimensions are shown in Figure 2 After the rough machining, the conduit is cleaned and transferred to the automatic or manual pressing machine for pressing. The pressing structure is shown in Figure 3 After the conduit is pressed, the reference of the conduit bottom hole and the spring nest and the outer wall of the conduit bottom hole are machined separately using a sleeve compound cutter. The machining method is shown in Figure 5 The specific working steps are as follows:

[0026] Step 1, change the machining method of the reference spring nest of the conduit pressing from direct machining to finished product size to increase the process size of the spring nest on the intake side by one step. In order to ensure the machining stability of the finish machining cutter, four process sizes are added to the machining test of the process size of a series of cylinder heads, and the process size in Table 1 is found out through process design.

[0027] Table 1 Process size table

[0028] Step 2, since the process size of the spring nest limiting depth of a series of engine cylinder heads is increased by 1.2 mm, the pressing depth of the intake and exhaust side conduits on the pressing equipment can be ensured to be consistent at 15±0.2 mm. The special gauge for measuring the pressing depth of the conduit is used to measure, and the data in Table 2 is obtained.

[0029] Table 2 Pressing depth measurement data

[0030] Cylinder head Press-in depth on intake side Press-in depth on exhaust side Workpiece 1 15.04 15.03 Workpiece 2 15.06 15.02 Workpiece 3 15.02 15.04 Workpiece 4 15.04 15.03 Workpiece 5 15.03 15.03

[0031] According to the measurement data in Table 2, the actual pressing depth on site can meet the requirements of the finish machining in the subsequent process within the tolerance range.

[0032] Valve seat pressure head improvement method: for a series of cylinder head design a special pressure head can be magnetic valve seat, ensure that the valve seat in the process of pressure installation will not be fixed firmly because of different structure and fall off, the pressure head before improvement relies on steel ball to block the valve seat pressure installation, see Figure 7 . The valve seat pressure head is redesigned and manufactured, the steel ball structure is changed to strong magnet, then combined and ground, the new valve seat head body adopts SKD11, 6 magnets are embedded along the body axis at equal intervals and bonded with strong glue, the new designed pressure head is shown in Figure 8 .

[0033] Pressure head limiting method: dead stop limiting, the present application is not limited to single dead stop limiting method, other spring nest depth positioning fixed pressure installation can use this processing method.

[0034] Step 3, design and manufacture spring nest finishing tool, and manufacture special-shaped PCD blade to process the inner and outer diameters and end face models respectively, and must be processed at the same time to ensure uniform stress and cutting amount in each direction. The tool structure is shown in Figure 4 , mainly including guide bar 1, tool holder and PCD blade 2, flange tool body 3, tool handle 4 and other parts, the hollow inside of the flange tool body 3 can avoid the guide pipe after pressure installation, the outer sleeve of the guide pipe bottom hole outer wall is machined, and the spring nest surface depth is machined to the final size, the tool holder is locked to the flange tool body 3 through screws, the guide bar 1 is connected to the flange tool body 3 through welding, and the flange tool body 3 is locked to the end face of the tool handle through the end face of the adjusting screw, which can adjust the tool body runout and blade height through the adjusting screw to ensure the machining accuracy, and the detailed machining arrangement is shown in Figure 6 . For pressure installation with the same pressure installation depth of intake and exhaust, it can be selected whether to use spring nest finishing tool for machining; for pressure installation with different pressure installation depth of intake and exhaust, spring nest finishing tool is needed for machining. The guide pipe bottom hole outer wall and depth need to be machined at the same time, otherwise the axial and radial stress of machining cannot be guaranteed, so the tool is designed to reserve allowance in two directions at the same time.

[0035] After spring nest finishing, the guide pipe pressure installation depth reaches the final size. With the guide pipe bottom hole as the positioning, the outer ring is sleeved into the spring nest, and the pass measurement is carried out by using the special gauge for measuring the guide pipe pressure installation depth, and the following table 3 data is obtained.

[0036] Table 3 exhaust side guide pipe pressure installation depth measurement data

[0037] Cylinder head Press-in depth on exhaust side Workpiece 1 16.22 Workpiece 2 16.25 Workpiece 3 16.23 Workpiece 4 16.23 Workpiece 5 16.24

[0038] According to the data statistics, it can be shown that the above working scheme can make the guide pipe valve seat equipment pressure installation compatible with the different pressure installation depth of the series of cylinder head intake and exhaust side guide pipe.

Claims

1. A process for press fitting a variable depth of a cylinder head guide tube for a range extended engine, characterized by The process comprises the following steps: Step one, rough machining of the depth of the pipe press fitting According to the relative position of the depth of the pipe bottom hole and the spring nest, the spring nest on the exhaust side is used as the rough machining reference to perform rough machining of the depth of the pipe press fitting, wherein: in order to ensure the consistency of the press head press-in position, the size of the spring nest on the exhaust side is left with a machining allowance in the axial and depth directions before press fitting; the press head body is made of SKD11, and six magnets are embedded along the axial direction of the body at equal intervals; the spring nest on the intake side is directly machined to the final size using a composite sleeve cutter, and does not need to be finished after press fitting; in order to ensure the consistency of the press head press-in position, the size of the spring nest on the exhaust side is left with a machining allowance in the axial and depth directions before press fitting, and is then machined to the final state using a composite sleeve cutter after press fitting; Step two, press fitting After rough machining, the pipe is transferred to an automatic or manual press fitting machine for press fitting, and the intake and exhaust side pipes are press fitted on the same press fitting equipment; Step three, finish machining of the depth of the pipe press fitting After the pipe press fitting is completed, the spring nest finish machining cutter respectively machines the pipe bottom hole and the spring nest reference and the outer wall of the pipe bottom hole to the final size, thereby completing the consistency of the depth of the intake and exhaust side pipes of the extended range engine cylinder cover.

2. The process for press fitting variable depth of cylinder head guide of range extended engine as claimed in claim 1 wherein The limiting mode of the press head is dead stop limiting.

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