Pump unit and handheld high pressure washer

A handheld high-pressure cleaning machine powered by a direct current and connectable to an external water source using a water pipe;

• wherein the handheld high-pressure cleaning machine comprises a spray gun comprising:
• a housing, wherein a motor, a transmission mechanism connected to the motor, and a pump driven by the transmission mechanism are provided in the housing;
• a handle having a front end and a rear end with the front end of the handle connected to the housing behind the motor;
• a detachable rechargeable battery pack coupled externally to the handle;
• and
• a nozzle connected to a water outlet of the pump whereby water from the external water source may be sprayed out through the nozzle;
• wherein the pump comprises a central chamber, a water inlet, a water outlet, a water inlet chamber connected to the water inlet, and a water outlet chamber connected to the water outlet, and wherein a plunger is disposed in the pump, an eccentric mechanism connected to the plunger drives the plunger to perform reciprocating motion, and
• wherein the water inlet chamber and the water outlet chamber are located at one end of the plunger, and the external water source enters the water inlet chamber through the water inlet, is discharged from the water outlet chamber after being pressurized by the central chamber, and is sprayed outward through the nozzle.