Engine generator

1. An engine generator comprising: a housing; an engine and a generator driven by the engine, the engine and the generator being disposed in the housing; a choke valve provided in an intake system of the engine; and an opening and closing mechanism for driving the choke valve,

wherein the opening and closing mechanism comprises:

a control shaft provided to a valve shaft of the choke valve to be rotatable relative to the valve shaft within a predetermined angular range;

a first urging member that is provided between the valve shaft and the control shaft and urges the valve shaft relative to the control shaft in a direction in which an opening degree of the choke valve decreases;

a restriction mechanism that sets a minimum opening degree of the choke valve by restricting a range of rotation of the control shaft;

a choke operating portion that is disposed on an outer surface of the housing and is connected with the restriction mechanism via a connection member, such that, upon operation, the choke operating portion drives the restriction mechanism in a direction in which the minimum opening degree of the choke valve decreases; and

a negative pressure mechanism that is driven by a negative pressure generated in the intake system or a crankcase of the engine during an operation of the engine to cause the control shaft to rotate in a direction in which the minimum opening degree increases within the range of rotation restricted by the restriction mechanism.

2. The engine generator according to claim 1 ,

wherein the opening and closing mechanism includes a framework member attached to the engine, and

wherein the restriction mechanism includes: a restriction mechanism lever rotatably supported by the framework member and having one end connected with the connection member; a restriction member provided to the restriction mechanism lever and restricting the range of rotation of the control shaft; a second urging member that urges the restriction mechanism lever relative to the framework member and generates a rotational resistance between the restriction mechanism lever and the framework member, the rotational resistance being derived from a frictional force; and an adjustment member that adjusts a preload applied to the second urging member.

3. The engine generator according to claim 2 , wherein the negative pressure mechanism comprises:

a diaphragm actuator including a main body whose interior is divided into chambers by a diaphragm such that a negative pressure is supplied to one of the chambers, and a rod connected with the diaphragm; and

a negative pressure mechanism lever rotatably supported by the framework member and connected with one end of the rod and with the control shaft.

4. The engine generator according to claim 1 , wherein the restriction mechanism restricts the range of rotation of the control shaft such that the minimum opening degree of the choke valve is set to half open when the choke operating portion is at an initial position.

5. The engine generator according to claim 1 , wherein:

the engine includes a recoil starter; and

the recoil starter has a handle provided on the outer surface of the housing in a vicinity of the choke operating portion.

6. The engine generator according to claim 1 , further comprising:

a fuel tank; and

a fuel cock provided to a fuel pipe connecting the fuel tank and the engine,

wherein an operating portion of the fuel cock is provided on the outer surface of the housing in a vicinity of the choke operating portion.