Method for manufacturing differential device and differential device

Patent metadata

Field	Value
Publication number	US-10539216-B2
Application number	US-201715621071-A
Country	US
Kind code	B2
Filing date	Jun 13, 2017
Priority date	Aug 8, 2016
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

A method for manufacturing a differential device includes a first step and a second step. The first step is to cast a differential case by pouring molten cast iron into, via a gate, a mold having, on a mold surface, a mark formation site that has a specific positional relationship to the gate. The second step is to fit the differential case with a ring gear and weld the differential case and the ring gear together entirely around a prescribed axis. In the second step, the differential case and the ring gear are welded together using a mark formed on the differential case by the mark formation site in the first step so that an overlap of welding does not occur in a portion of the differential case formed near the gate of the mold.

First claim

The invention claimed is:

1. A method for manufacturing a differential device, comprising:
a first step of casting a differential case by pouring molten cast iron into, via a gate, a mold having, on a mold surface, a mark formation site that has a specific positional relationship to the gate; and
a second step of fitting the differential case with a ring gear and welding the differential case and the ring gear together entirely around a prescribed axis,
wherein, in the second step, the differential case and the ring gear are welded together using a mark formed on the differential case within the mark formation site in the first step so that an overlap of welding does not occur in an area where a pearlite ratio is higher in the differential case.

2. The method for manufacturing the differential device according to claim 1 , wherein, in the second step, the differential case is placed using the mark so that the area where the pearlite ratio is higher is located in a specific position different from a starting position of the welding.

3. The method for manufacturing the differential device according to claim 2 ,
wherein the mark is a notch provided on a part of an outer peripheral surface of a cylinder of the differential case to be fitted with the ring gear, and
in the second step, the differential case is held by a jig having a positioning site capable of being fitted with the notch and the differential case is placed in a prescribed place, and thereby the area where the pearlite ratio is higher is located in the specific position different from the starting position of the welding.

4. A differential device, comprising:
a differential case made of a casting containing cast iron as a main component; and
a ring gear that has an opening with which a cylinder of the differential case is fitted and is welded with the differential case entirely around a prescribed axis,
wherein, in the differential case, a pearlite ratio is higher in a partial area in a round direction of the cylinder than in another area, and the differential case has a mark having a specific positional relationship to the partial area where the pearlite ratio is higher, and
an overlap where a base point and an end point of a welding overlap is located in an area different from the area where the pearlite ratio is higher.

5. The differential device according to claim 4 , wherein the mark is a notch provided on a part of an outer peripheral surface of the cylinder.

6. The differential device according to claim 5 ,
wherein a space is provided between a fitting site where the differential case and the ring gear are fitted together and a welding site where the differential case and the ring gear are welded together, and
the space communicates with an outside of the differential case via the notch as the mark.

Assignees

• Subaru Corp

Inventors

• Shirakawa Yusuke

Classifications

• F16H48/12

  without gears having orbital motion · CPC title

• F16H48/42

  characterised by features of the input shafts, e.g. mounting of drive gears thereon · CPC title

• F16H2048/405

  characterised by features of the bearing of the rotating case · CPC title

• F16H2048/385

  of the ring or crown gear · CPC title

• F16H48/40 Primary

  characterised by features of the rotating cases · CPC title