Cooling system

A cooling system for cooling an internal combustion engine, comprising:

• an internal passage that circulates cooling water inside the internal combustion engine;
• a water pump provided in one end side external passage connected to one end portion of the internal passage;
• a water flow switching unit configured to execute a water flow switching control that switches the cooling water flow in the internal passage between a forward flow directed from the one end portion to the other end portion of the internal passage and a reverse flow directed from the other end portion to the one end portion;
• an other end side external passage connected to the other end portion;
• a first communication passage and a second communication passage connecting the one end side external passage and the other end side external passage;
• and
• switching valves configured to switch a forward flow and a reverse flow of the cooling water discharged from the discharge port of the water pump, wherein the forward flow passes the internal combustion engine through the one end side external passage, and returns from the other end side external passage to the inlet port of the water pump, and the reverse flow passes the internal combustion engine through the first communication passage, and through the other end side external passage, and returns from the one end side external passage and the second communication passage to the suction port, wherein
• the water flow switching unit executes the water flow switching control by driving the water pump while controlling the switching valve,
• the switching valve has a first valve, a second valve, a third valve, and a fourth valve, all of which are two-way valves,
• the first valve is provided in the second communication passage,
• the second valve is provided between a branch portion to the first communication passage and a branch portion of the second communication passage in the one end side external passage,
• the third valve is provided between a branch portion to the first communication passage and a branch portion of the second communication passage in the other end side external passage,
• the fourth valve is provided in the first communication passage, and
• the water flow switching unit executes the water flow switching control in which the forward flow is formed by opening the second valve and the third valve while closing the first valve and the fourth valve and driving the water pump, and the reverse flow is formed by opening the first valve and the fourth valve while closing the valve and the third valve and driving the water pump.

A cooling system for cooling an internal combustion engine, comprising:

• an internal passage that circulates cooling water inside the internal combustion engine;
• a water pump provided in one end side external passage connected to one end portion of the internal passage;
• a water flow switching unit configured to execute a water flow switching control that switches the cooling water flow in the internal passage between a forward flow directed from the one end portion to the other end portion of the internal passage and a reverse flow directed from the other end portion to the one end portion;
• an other end side external passage connected to the other end portion;
• a first communication passage and a second communication passage connecting the one end side external passage and the other end side external passage;
• and
• switching valves configured to switch a forward flow and a reverse flow of the cooling water discharged from the discharge port of the water pump, wherein the forward flow passes the internal combustion engine through the one end side external passage, and returns from the other end side external passage to the inlet port of the water pump, and the reverse flow passes the internal combustion engine through the first communication passage, and through the other end side external passage, and returns from the one end side external passage and the second communication passage to the suction port, wherein
• the water flow switching unit executes the water flow switching control by driving the water pump while controlling the switching valve,
• the switching valve has a first valve and a second valve, each of which is three-way valve,
• the first valve is provided at a branch portion between the one end side external passage and the second communication passage,
• the second valve is provided at the branch portion between the other end side external passage and the first communication passage, and
• the water flow switching unit executes the water flow switching control that drives the water pump while switching the first valve and the second valve so as to form the forward flow, and drives the water pump while switching the first valve and the second valve so as to form the reverse flow.

A cooling system for cooling an internal combustion engine, comprising:

• an internal passage that circulates cooling water inside the internal combustion engine;
• a water pump provided in one end side external passage connected to one end portion of the internal passage;
• a water flow switching unit configured to execute a water flow switching control that switches the cooling water flow in the internal passage between a forward flow directed from the one end portion to the other end portion of the internal passage and a reverse flow directed from the other end portion to the one end portion;
• a bypass passage configured to branch the cooling water from the dividing portion of the one end side external passage and rejoin the cooling water to the other end side external passage connected to the other end portion side of the internal passage;
• a check valve provided in the bypass passage;
• a three-way valve provided between the dividing portion of the one end side external passage and the one end portion;
• a communication passage connecting the three-way valve and an other end side external passage connected to the other end portion;
• and
• the water flow switching unit executes the water flow switching control by controlling the water pump and the three-way valve.