A conversion device, comprising: a vehicle body, wherein the valve body is provided with a valve body air inlet path, a first valve body air outlet path, and a valve body passage; a valve cover, wherein the valve cover is rotatably mounted on the valve body; and the valve cover is provided with a first valve cover passage, a second valve cover passage, and a third valve cover passage; and a first shrinkage member, wherein the first shrinkage member is provided at a first port of the second valve cover passage, the valve cover is configured to be rotatable relative to the valve body, so as to be switched between a first mounting position and a second mounting position, wherein in a situation that the valve cover is in the first mounting position, the valve body air inlet path, the first valve cover passage, the valve body passage, the second valve cover passage, and the first valve body air outlet path are in communication with each other in sequence, a first port of the second valve cover passage is in communication with an air outlet end of the valve body passage, a second port of the second valve cover passage is in communication with an air inlet end of the first valve body air outlet path; the first shrinkage member is configured to slow down a gas in the valve body passage entering the second valve cover passage, and two ports of the third valve cover passage are configured to be blocked by a side wall of the valve body; and in a situation that the valve cover is in the second mounting position, the valve body air inlet path, the third valve cover passage, the valve body passage, the second valve cover passage, and the first valve body air outlet path are in communication with each other in sequence, the first port of the second valve cover passage is configured to be blocked by the side wall of the valve body, the second port of the second valve cover passage is configured to make the air outlet end of the valve body passage in communication with the air inlet end of the first valve body air outlet path, and two ports of the first valve cover passage are configured to be blocked by the side wall of the valve body. a vehicle body, wherein the valve body is provided with a valve body air inlet path, a first valve body air outlet path, and a valve body passage; a valve cover, wherein the valve cover is rotatably mounted on the valve body; and the valve cover is provided with a first valve cover passage, a second valve cover passage, and a third valve cover passage; and a first shrinkage member, wherein the first shrinkage member is provided at a first port of the second valve cover passage, the valve cover is configured to be rotatable relative to the valve body, so as to be switched between a first mounting position and a second mounting position, wherein in a situation that the valve cover is in the first mounting position, the valve body air inlet path, the first valve cover passage, the valve body passage, the second valve cover passage, and the first valve body air outlet path are in communication with each other in sequence, a first port of the second valve cover passage is in communication with an air outlet end of the valve body passage, a second port of the second valve cover passage is in communication with an air inlet end of the first valve body air outlet path; the first shrinkage member is configured to slow down a gas in the valve body passage entering the second valve cover passage, and two ports of the third valve cover passage are configured to be blocked by a side wall of the valve body; and in a situation that the valve cover is in the second mounting position, the valve body air inlet path, the third valve cover passage, the valve body passage, the second valve cover passage, and the first valve body air outlet path are in communication with each other in sequence, the first port of the second valve cover passage is configured to be blocked by the side wall of the valve body, the second port of the second valve cover passage is configured to make the air outlet end of the valve body passage in communication with the air inlet end of the first valve body air outlet path, and two ports of the first valve cover passage are configured to be blocked by the side wall of the valve body.