Gear pump

Abstract

The present invention provides a gear pump with a simple structure and capable of easily regulating the discharging flow rate. The gear pump includes: a first pump (20) constructed from a first drive gear (21) rotated by driving of a drive shaft (11) and a first driven gear (22) rotatably arranged coaxially with a rotary shaft (12); and a second pump (30) constructed from a second drive gear (31) rotatably provided coaxially with the rotary shaft and a second driven gear (32). The rotary shaft allows the first driven gear and the second drive gear to engage with and disengage from each other in a rotation direction by movement to an axial direction. When the discharge pressure is higher than predetermined pressure, rotation of the first driven gear is not transmitted to the second drive gear and only the first pump operates. When the discharge pressure becomes the predetermined pressure or less, the rotation of the first driven gear is transmitted to the second drive gear and the first and the second pumps operate.

Description

technical field [0001] The present invention relates to a gear pump driven by a driving source such as an engine, and specifically relates to a variable displacement gear pump. Background technique [0002] The discharge flow rate of a gear meshing pump is determined by the capacity corresponding to the tooth height and tooth width, and the rotation speed of the gears (pump rotation speed). When such a gear pump is used as an oil pump for a vehicle, since the capacity of the oil pump depends on the engine speed as the driving source, depending on the operating conditions of the vehicle, the discharge flow rate of the oil pump may not reach the required flow rate of the supply part. In some cases, the required amount of oil may not be properly supplied. [0003] Conventionally, in order to cope with such a problem, variable displacement gear pumps disclosed in Patent Documents 1 to 4 have been proposed. The gear pump of Patent Document 1 has an oil pressure regulating valve...

AI Technical Summary

Problems solved by technology

[0008] In the above-mentioned conventional variable displacement type pump, in the pump whose discharge capacity is adjusted by the mechanical structure, a plurality of mechanisms such as valves are added to the gear pump, which leads to the complexity of the peripheral structure of the gear pump and the reduction in the number of parts. increase, there is a possibility of high product costs

In addition, in the configuration in which the meshing width of the gears is changed, the mechanism of the gear pump itself becomes complicated, resulting in an increase in the number of parts or a problem in size.

In addition, when the mechanism of the gear pump becomes complicated, the requirement for dimensional accuracy also increases correspondingly, so there will also be problems in the durability of the pump.

In addition, in pumps with variable input rotation speed, there is a concern that the control mechanism and procedures for the above-mentioned purpose will be complicated.

Images