Engineering Breakthrough in Synchronizer Lock Pin Positioning Technology

This article presents a positioning device designed for riveted synchronizer assemblies that incorporates built-in locking pins. The device includes specially designed positioning blocks and other components to address specific challenges, such as the tendency of the locking pin to wobble and the difficulty of maintaining perpendicular alignment with the synchronizer cone during the riveting process. The article details the device’s structure and its intended use, highlighting how it can enhance both yield and efficiency in production.

 

1 Introduction

A synchronizer is a device that ensures the smooth engagement of meshing gears during gear shifts. To achieve this, the circumferential speeds of the meshing rings of the gears must be equal. If these speeds are not synchronized, it can lead to impacts and noise between the gear rings, which can shorten the lifespan of the gears. To facilitate gear shifting, synchronizers are commonly installed between frequently used gears in automobile transmissions. The most popular type of synchronizers are inertia synchronizers, which come in both lock-ring and lock-pin designs. These synchronizers are widely used in various vehicle models to enhance power and fuel efficiency during gear shifts and acceleration.

 

2.1 Current Problems
In the current production process for locking pin synchronizers, some require riveting. This process involves inserting a locking pin through the retaining ring and synchronizer cone via the center of the synchronizer sleeve, followed by riveting them together. The specific structure and assembly requirements are detailed in Figure 1.

A locking pin synchronizer generally comprises a synchronizer sleeve, retaining ring, synchronizer cone, locking pin, and guide post. These components are assembled into a single piece by riveting the ends of the locking pin. The perpendicularity of the locking pin and synchronizer cone after riveting directly affects the positional accuracy and parallelism requirements between the locking pin and the reference surface B of the synchronizer cone. Consequently, this has an impact on the shifting force and smoothness during the shifting process.

During riveting, the locking pin is passed through the retaining ring and sleeve, and is then vertically inserted into the synchronizer cone. It is secured using a pin driver. However, when riveting with a pin driver, the locking pin tends to swing left and right. Additionally, there is no effective structural positioning relationship between the locking pin and the synchronizer cone disc, making it challenging to position accurately in the external structure. The existing technology does not effectively position the locking pin and synchronizer cone disc, which significantly affects their verticality when riveting.

The alignment and parallelism of the locking pin with the synchronizer cone disc in the locking pin synchronizer assembly are critical (refer to the technical requirements in Figure 1 for specifics). Any misalignment seriously impacts both the quality rate and production efficiency of the locking pin synchronizer assembly during riveting.

To improve the effectiveness of riveting devices, a new positioning device is necessary. This device aims to resolve the issue of improper installation of the locking pin and synchronizer cone during the riveting process, which significantly affects the quality of the lock-pin synchronizer assembly. By ensuring the perpendicular alignment and correct positioning of the locking pin and synchronizer cone during riveting, this positioning device enhances the assembly efficiency and increases the pass rate of the lock-pin synchronizer assembly.

 

2.2 Technical Solution for Positioning Device for Riveted Internal Locking Pins

To address the technical issues mentioned earlier, a positioning device was developed for riveted internal locking pins in lock-pin synchronizer assemblies. The structure of this positioning device is illustrated in Figure 2. It consists of several CNC components: an internal positioning block (1), a centering pressure plate (2), an opening washer (3), a fastening bolt (4), a base plate (5), and a removable center positioning disk (6) with a horizontal surface, which is firmly attached to the base plate (5).

Two internal positioning blocks (1) are installed on either side of the center positioning disk (6) and extend into the interior of the lock-pin synchronizer assembly. These blocks are responsible for vertically positioning the two locking pins within the assembly. The positioning surfaces on these blocks feature vertical angular notches.

Above the center positioning disk (6), there is a center positioning pressure plate (2) that limits the movement of the lock-pin synchronizer assembly. An opening gasket (3) is placed on top of the center positioning pressure plate (2). The center positioning pressure plate (2) and the opening gasket (3) are securely connected to the base plate (5) and the center positioning disk (6) at the axis of the lock-pin synchronizer assembly using fastening bolts (4).

3. Using the Riveted Built-in Locking Pin Positioning Device

The structure of the positioning device is illustrated in Figure 3. The base plate and center positioning plate are connected using a positioning pin and sleeve, allowing for easy removal while ensuring that both plates are securely locked in their horizontal position. Alternatively, bolts that match the specifications of the positioning pin and sleeve can also be used for attachment.

A synchronizer cone is mounted on the center positioning plate, where the locking pins are pre-positioned. Additionally, two built-in positioning blocks are fixed on either side of the center plate. These blocks extend into the lock-pin synchronizer assembly and serve to vertically align the two locking pins within the assembly. Each positioning block features vertical angular notches that make contact with the guide cylindrical surfaces of the locking pins. This design ensures accurate positioning and prevents the locking pins from moving during riveting and punching due to the pin driver.

Above the center positioning plate is another plate that serves to limit the movement of the synchronizer assembly. This setup accurately positions the retaining ring along the axis for riveting. A split gasket is installed on the center positioning plate, while the centering pressure plate and split washer are removable. They connect to both the base plate and center positioning plate at the axis of the synchronizer assembly via fastening bolts. Utilizing these bolts to connect the base and center plate guarantees the coaxial alignment of all mating parts and allows for quicker replacement of the synchronizer assembly components after riveting.

To operate this positioning device, first remove the centering pressure plate and split washer. After loosening the fastening bolts by approximately one thread pitch, the split washer and centering pressure plate can be easily taken off. The components of the lock-pin synchronizer assembly that need to be installed are then placed in their corresponding positions on the centering plate. The three locking pins are secured to the synchronizer cone through an interference fit, ensuring precise alignment and integration.

Two built-in locating blocks extend into the lock-pin synchronizer assembly, and their uniquely shaped vertical notches accurately contact the guide cylindrical surfaces of the locking pins, securing two of the three evenly spaced locking pins around the synchronizer assembly. These three locking pins are pre-installed and fixed to the synchronizer cone with an interference fit, forming a cohesive unit. By employing the principle of placing two pins on each side and facilitating ease of installation, securing two of the locking pins helps pre-position both the locking pins and the synchronizer cone prior to riveting, limiting their circumferential rotation relative to the center of the centering plate.

The locating blocks effectively prevent any movement of the locking pins during the riveting process. Once in place, the synchronizer assembly is bolted together through the centering plate and split gasket, ensuring that the concentricity of the circular arrangement formed by the three locking pins aligns with the center of the synchronizer cone on the centering plate. This alignment must adhere to the required installation tolerances. After the lock-pin synchronizer assembly is installed, the opening gasket can be removed, allowing for the quick loosening of the center positioning pressure plate. This streamlined process facilitates the rapid replacement of parts in the lock-pin synchronizer assembly, ultimately improving both the qualification rate and efficiency of the assembly during mass production.

 

4 Conclusion

The key concept behind the riveted internal locking pin positioning device centers on the innovative structural design of several CNC turning components, including the base plate, centering plate, internal positioning block, centering pressure plate, open gasket, and fastening bolt. This device features two internal positioning blocks that extend into the lock-pin synchronizer assembly. These blocks have specially shaped vertical angled notches that make precise contact with the cylindrical surface of the locking pin guide.

This design effectively positions two of the three locking pins evenly around the circumference of the lock-pin synchronizer assembly, establishing a clear positional relationship between the unriveted synchronizer cone surface and the locking pins. This arrangement restricts the movement of the locking pins and ensures that the coaxial alignment of the three locking pins with the centering plate remains within the required installation tolerances. As a result, it meets the technical specifications for the positional accuracy of the synchronizer assembly post-riveting.

Additionally, the centering pressure plate and easily removable open gasket facilitate the rapid replacement of synchronizer assembly components, enhancing the efficiency of mass production for lock-pin synchronizer assemblies.

Compared to existing technologies, the riveted internal locking pin positioning device offers several advantages: it employs two internal positioning blocks extending into the lock-pin synchronizer assembly, which align precisely with the locking pin guide’s cylindrical surface. This, combined with the overall design of the positioning device, ensures a defined positional relationship between the unriveted synchronizer cone surface and the locking pins through the positioning surfaces. This guarantees the perpendicularity and alignment between the locking pins and the synchronizer cone, preserving the coaxiality of the three locking pins with the center positioning disc. Moreover, the device features a simple, rational, and highly practical structure that improves the quality of mass-produced lock-pin synchronizer assemblies.

 

 

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